Soft Focus on the 24-70 GM

[Madafied]

Greetings.

I bought the 24-70 GM in November of last year and since have been hit or miss with focus. A majority of the shots are very soft on the focal point and for the money I would expect much better. I also own the 50mm 1.8, 70-200 GM, and 24 GM and consistently get super sharp images from all of those. Why would I only have problems with the 24-70? Is this a common thing? I've tried looking it up and not too much is said other than some saying focus after F7 is not good or soft focus at 70mm. It happens in all conditions whether low light, good light, flash, indoor, outdoor, landscape, or portraits. I hardly pull it out of the bag as I can't take the chance of it being soft. I should absolutely love it if I paid that enormous amount of money for it, but I feel the complete opposite about it. 

Does anyone know of any issues with the lens or how I can go about getting the problem fixed? I'm at the point I want to get rid of it, but I can't sell it to someone knowing that there may be something wrong with it. I wouldn't want that to happen to me. Not to mention I paid a high price for the lens and don't want to lose the money I dropped on it.

The firmware is updated and there has been no damage. I shoot using an a7iii and a9 with updated firmware.

Any help would be appreciated.