Ok, two thoughts.
One thing: try installing a replacement keyboard from a reputable vendor, such as Swiftkey Swype, or Fleksy, and see if that solves the problem.
My other idea is to ask if you have Facebook Messenger installed? It's been a while, but I recall that the stupid "chat heads" feature can obscure screen tap elements without being obvious. Usually it's the top left corner, though. Anyway, that's an idea - turn off the chat heads feature, or just uninstall FB Messenger temporarily to see if that solves the issue. Of course, if you have another app that permanently puts an element over the screen like chat heads does - like the Brave browser, for example - maybe that app is the culprit?
One thing: try installing a replacement keyboard from a reputable vendor, such as Swiftkey Swype, or Fleksy, and see if that solves the problem.
My other idea is to ask if you have Facebook Messenger installed? It's been a while, but I recall that the stupid "chat heads" feature can obscure screen tap elements without being obvious. Usually it's the top left corner, though. Anyway, that's an idea - turn off the chat heads feature, or just uninstall FB Messenger temporarily to see if that solves the issue. Of course, if you have another app that permanently puts an element over the screen like chat heads does - like the Brave browser, for example - maybe that app is the culprit?