Errors in exporting png and stl files

Hi there!

I started teaching SketchUp to my 12 year old students during the Covid lockdown, with reasonable succes. However, now I’m running into several problems exporting PNG and STL files with some of my students (not on my own account luckily).
My students are able to work on their projects, save in their OneDrive, but some are unable to export the files to PNG and STL. They do get the export screen, but whenever they click Export button, nothing happens. Some of them get a message there is something wrong with WiFi connection, but not all of them or all of the time. The problem seems to be mostly happing on Chromebooks, but that is the most common computer in use amongst the kids.
Anybody any experience with this? Tips?
Thanks in advance,