Auto-translated
I know of a similar bug:
When you click on the hint bar (which is also the chat input bar) on the adventure map, the developers likely intended for it to start the chat text input (like when you press Tab). However, this is implemented with a bug, and when you click on this bar, the keyboard switches to input mode (the spacebar and other keys don't work), but the text is also not entered. In the hint/input bar itself, hints for objects and other text are not displayed, and after the screen is updated (switching the current hero, etc.), an underscore starts to appear, as if you were starting to enter text.
This mode cannot be canceled with the spacebar or Enter. However, if you press Tab, it switches to normal text input mode, where you can enter text, send it with Enter, or cancel with Esc.
So, to exit this situation, you need to press Tab and then Esc.
I have occasionally seen this bug on streams; it mainly interferes with the non-working spacebar and the non-displayed hints. However, there are no problems with saving the game or exiting (the S hotkey, of course, doesn't work, nor do Esc and F4 for minimizing the game, but you can still save/exit with the mouse). Perhaps this is a different type of bug.
I would also like to note that, apparently, during this situation, the HD hotkeys work, and the original game's hotkeys do not. In any case, not all hotkeys stop working.