I work with commandblocks all the time and I only recently ran into this error. It started on minecraft fabric 1.16.4 and then even in vanilla minecraft versions 1.16.4, 1.16.5 and the snapshot versions of 1.17. I don't seem to be able to recreate this bug, it just randomly appears but is most likely to appear when using the execute commands with all its variables such as "~, @, [], {}. It always delets the complete command section when the letter "a" is typed :/
I work with commandblocks all the time and I only recently ran into this error. It started on minecraft fabric 1.16.4 and then even in vanilla minecraft versions 1.16.4, 1.16.5 and the snapshot versions of 1.17. I don't seem to be able to recreate this bug, it just randomly appears but is most likely to appear when using the execute commands with all its variables such as "~, @, [], {}. It always delets the complete command section when the letter "a" is typed :/