I used to be able to block text and type a letter which would replace the
entire text. Now, when I block the text and type a letter, the letter is
just added at the end of the blocked text.

Also, I used to be able to block text and press "backspace" and the block
text would be erased. Now when I block text and press "backspace," the
cursor just goes to the beginning of the blocked text.

WHY IS IT DOING THIS!?!!!

Blocked text + delete works just fine though.