Help with AF tracking troubleshooting

[silsrf]

I recently purchased a refurb A7lll on Amazon. I was unable to get continuous auto focus with a flexible spot to track while in movie mode.

I was trying on Canon 16-36 Mk II and Canon 24-70 Mk II a Sony 50mm FE E-Mount and a Samyang 35 E-Mount.

The the Canons using a metabones Mk V adapter.

On the Canons the AF would constantly search and chatter, quite a large spread, out to infinity (and beyond) and back, never locking on at all. On the Samyang it would not even search, the flexible box would come up, but the focus did not even attempt to search or lock.The camera came at firmware 1.10. I upgraded it to the latest (2.10), but it made no difference.

Everything else appears to be functioning correctly.

I am replacing the body thru Amazon, but in preparation would love some help on how to best diagnose where the issue lies if it persists with a new body. Thanks very much for you help.