TortoiseSVN Will not let me check out a file in UE4

So TortoiseSVN is set up and working with a repository on a server and local working file. UE4 is set to use Source Control. That all seems to be behaving as it should, we can see which files another user has checked out, and which need to be updated.

The problem is that when we want to check out or save an asset from UE, it will check it out and then say file already checked out by “MyUsername” and therefore will not let me check it out again or save the file (ie the checkmark is blue, not red).

Anyone else come across this issue before?