What should I do if the touch buttons do not work in Lineage 14.1?

Question

lineageOS

,Hello.
I recently installed LineageOs 14.1 (Android 7.1.) on my Samsung Galaxy Tab E. And at the beginning, the button of recent applications did not work. I tried to add a line to the /system/usr/keylaout/Generic.kl file:
key 254 APP_SWITCH, but it did not help. And after some use, the back button also stopped working.
Please tell me how can this be fixed?