Normally when I export files PocketMoney to my desktop (all accounts) the file size is about 1.2MB, whether .qif or .csv.
But today the file sizes were 12KB, 16KB or 28 KB, depending on the encoding that I tried (all except Greek) and when opened in Excel they contained only 100 rows of data.
Turns out I had inadvertently applied a filter, and this wasn't apparent to me from the main screen.
So if your exported files are empty or much smaller than expected, scroll down in the main screen, tap All Transactions and check to see if a filter is applied. Tap on the Filter button and Reset Filter if necessary.