After I updated the a6300 firmware I began getting the card compatibility error message. To note, I used these cards just last week (and for the past 4 months) shooting 4k in 100mb mode without any problems. They work in 4k 100mb mode on my gx85 as well. The only difference is the firmware update.

 

Any thoughts?

Sandisk used to offer a downloadable low level reformatting tool. It's possible Lexar may as well, check their site for support software.

it's possible the Card needs to be reformated to be recognized by the New Firmware.

http://www.lexar.com/support/downloads.html

 

Alternatively , you might try reformatting the card by use of the in camera function.

OldNoob, thanks for the info. I should have stated that I tried something similar to what you mentioned. I wasn't able to find a formatting program on Lexar's site but I did find one at https://www.sdcard.org/downloads/formatter_4/

 That software allowed me to begin recording at the 4k 60mb rate. I also had to reset the camera and reformat the card in the camera. At this point I'm able to record only at 4k 60mb. It is an oddity but I wonder if that's part of Sony's overheating resolution for the a6300. It may just be my cards but since they work in the gx85 I'm not sure what the issue is. My order of the XT2 just came in so I'll see if  I'm having the same problem with that one. Unfortunately, I cannot try another card since all four of my 4k capable cards are Lexar 633x.

Well, I tried the cards in other 4k cameras and they seem to work fine. At a loss on what to do. I've reformatted on my mac, in the camera and using a low level formatting program. The best I can get without the 'use a U3 card' is 4k at 60mb.

From my personal experience, Lexar cards are rated much higher than they actually perform. They also tend to fail on me quite frequently, specifically the 633x model.

 

Sandisk for life!

Yep it's hard to beat the Sandisk.

I've even had Sony brand SD cards not read in my a6000

I just realized something,, you say you can no longer record at 100mbs after the firmware update? This actually may be intentional and part of Sony's solution for addressing the "Overheating" complaints many have launched with regard the a6300. Slowing down the write rate would use less power and result in less heat.

On a side note,,, while the max read speed of the Lexar 633x may be 95mbs it seems the official max "write" speed is only 45mbs. and it's constant write speed is 10mbs  http://www.lexar.com/products/memory-cards/sd/Lexar-Professional-633x-SDHC-SDXC-UHS-I-cards.html#SKU=LSD512CBNL633

I just realized something,, you say you can no longer record at 100mbs after the firmware update? This actually may be intentional and part of Sony's solution for addressing the "Overheating" complaints many have launched with regard the a6300. Slowing down the write rate would use less power and result in less heat.

 

On a side note,,, while the max read speed of the Lexar 633x may be 95mbs it seems the official max "write" speed is only 45mbs. and it's constant write speed is 10mbs  http://www.lexar.com/products/memory-cards/sd/Lexar-Professional-633x-SDHC-SDXC-UHS-I-cards.html#SKU=LSD512CBNL633

 

Which would make sense why Sony would disable it for 100 mbps video. 100 megabits is 12.5 megabytes, which the 633x cards are not capable of. That's the bare minimum definition of UHS-I, which I guess Lexar is totally happy with; the bare minimum.

 

In stark contrast, the budget Sandisk Ultra 40mb/s, which is a few generations old at this time, bottoms out at 17mb/s write speed on an a6000, also a generation old.

I just realized something,, you say you can no longer record at 100mbs after the firmware update? This actually may be intentional and part of Sony's solution for addressing the "Overheating" complaints many have launched with regard the a6300. Slowing down the write rate would use less power and result in less heat.

 

I thought that as well but yesterday I formatted one of the lexar's in the fuji xt2 and it now works in the sony shooting 4k at 100mb. There's one more thing to check, this may be one of the cards that I did NOT format on my mac using OS software. That shouldn't make any difference but I'll double check and post the results. I guess I'm sticking with Sandisk from now on. I had a sandisk fall apart on me and haven't sent it in for replacement yet so I thought I'd try the Lexar. Hopefully I don't have four duds that can't be used in the Sony.

On a side note,,, while the max read speed of the Lexar 633x may be 95mbs it seems the official max "write" speed is only 45mbs. and it's constant write speed is 10mbs  http://www.lexar.com/products/memory-cards/sd/Lexar-Professional-633x-SDHC-SDXC-UHS-I-cards.html#SKU=LSD512CBNL633

 

I saw that before and it didn't impact my shooting until this week, guess you get what you pay for.

Nevermind, user error, mostly. I bought another pack on sale and it's when they switched the U3 to U1 - same price of course. I thought I was using the old ones but got the new ones mixed in. However, I doubt I'll be buying Lexar cards again. You literally have to read the actual fine print. lesson learned