"The image part with relationship ID rld8 was not found in the file"

I have a Mac Air (running High Sierra) user whose images have been replaced with red Xs and the message "The image part with relationship ID rld8 was not found in the file" in word (o365) files from our offices shared network.

this typically happens when she works with the files on the network (vs saving them locally first).

so she will open a word (o365) file on the network, make an edit and save. it will take a long time to save and then when it is reopened (by any user, not just by herself) the images will be missing. this happens on site (in the office) and offsite (running form home through VPN) and it happened before she updated to high sierra as well.

i have read that best practice is for users to save files locally before editing and will encourage her to do that with more consistency but wanted to find out if there was anything else she should be doing  as well.