You may need to turn buffering off on the filehandle you're using to write to the file. Also, if it weren't for other records immediately disappearing I'd suspect you don't truncate the file in which case the last record would stick around - but then it would have to happen for all records and wouldn't disappear on next refresh..

I agree, we need some code here before we can give any sort of actual advice.

Makeshifts last the longest.