The first location was on network drive, ...
Eh. That's most likely the root of the issue.
(Working with files over the network is very dangerous. Working with databases over the network is safe, working with web servers is safe, working with files in live mode where the file is kept opened for a long period of time / is saved incrementally is not. This is true for all files, and particularly for big ones. The main issue is that the network sometimes says 'ok, I wrote what you wanted where you wanted' but that 'ok' is actually susceptible to the network connection failing some time later and leaving the write incomplete. The application frequently has no means to even know about the failure because it closed the relevant handles thinking that everything went fine. Yet the file on the server is in a zombie state with the writes that only completed partially. This is why Microsoft, for example, required that nobody works with MDB files over network shares - people still did, but they were always on their own, that could fail horribly and it did fail horribly losing data plenty of times. We have been considering just copying MAP files accessed over the network locally and copying them in full back after they are saved, but there are obviously huge performance / space repercussions.)