I normally use Blender 2.79b and when I use 2.91.2 my Logitech K800 keyboard has “opposite lag” for the “A” key that I cant create models, I have tried a second K800 keyboard and its the same and if I use a wired keyboard I have the same problem. Something that I have noticed is if I’m in edit mode with a model and I’m trying to select all vertices with the “A” key it will only respond if I press “A” fast so I’m selecting and deselecting with “A” on and off fast and that works but also impossible to work with and if I press “A” slow to select/deselect it does not work, but so far all the other keys I’ve tried work ie: scale, grab, tab, XYZ etc so its only for the “A” key. Everything on my PC works with Blender 2.79b and I have reinstalled 2.91.2 a few times too to see if it helped but it hasn’t.
My PC specs:
i7 4930k CPU @ 3.4GHz turbo @ 3.9 GHz
RTX 2080 Ti 11GB
32 GB 1866 DDR3 Ram
Asus Rampage 4 Black edition motherboard
Blender running off an SSD (SATA)
Windows 10 Pro