When copying track numbers from file name to tag and the numbers are three figures (like track no. 123) the numbers upto 008 are correct in Windows 10 File Explorer. Then comes another 008 and then a double 009 and this is repeated at 018, 019, 028, 029 and so on. The inbetween number are also affected by this behaviour. The track number ("spår") shown in mp3tag are curiously enough correct. I attach some example screen dumps.
I have not tested any other format like 01 or 0123.
@ohrenkino This indeed seems to be the reason for the corrupt track numbering in Windows File Explorer. I removed the zero padding and the problem disappeared Thank you for your quick response! I have been using mp3tag for several years now and I have never observed this misbehaviour in Windows.