In the Linux version (don’t know about anything else) a space is automatically appended to the end of the file name you give an export so you end up with video.mp4_ (where the line represents the space).
I know this seems really petty but it prevents you doing certain things with it until you realise what’s going on and rename it yourself. That had me stumped for a while when it first happened because the movie wouldn’t play and I couldn’t copy it to another device. You can’t actually see the space until you choose to rename the file.
I’m sure it will catch me out again. [forehead slap] 