I was wondering if it was because somebody else has opened the file with exclusive access.
But I don't think so, as you would get a message to say the "file is in use by...." rather than that it is locked.
Do you happen to have 'preview' active in your Windows File Explorer?
I have not seen this with a PLN, but have had problems when trying to save a PDF.
If someone has the file selected in Windows File Explorer with the preview active, that is enough to lock the file and prevent it from being overwritten.
So make sure that your (or anyone else) does not have the file selected in Windows File Explore.
I don't think there is much you can do about this (if it is the cause of your problem) except for turning the file preview option off on all machines that access these files.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11