Holding down Alt key will make A key unusable.
Environment: Win 10; I use Left Alt for sneak and A for strafing left, sneaking with Left Alt disables me from strafing left. The issue exists on Right Alt too.
Cannot find any existing report via search (innocent)
Does not apply when A is pressed before Alt
To reproduce: Map one of Alt (the issue exists on either one) and key A to, for example:
Sprint or Sneak & Move Forward
Jump a& Sneak (when in creative, 'shifts' without descending)
Assumption: Alt+A is some sort of (useless?) combo I am not aware of.
Related issues
Comments


Hardware issue, see MC-54194
Cannot reproduce in 1.13-pre2, even with Left Alt mapped to Sneak.
This is most likely an issue with your keyboard. check that you can hit this combination outside of Minecraft.