However, I suspect that no-one who posts here can advise you how to avoid this, sorry. I am somewhat surprised if MS requires a continuous internet link. I realise it needs to check the validity of your licence but I thought this was just an initial check on first opening the program.
Exactly which version of Movie Studio do you have? Just as an experiment I opened MS2025 Suite, opened a project, began editing and then deliberately turned off my Ethernet (Internet) connection. No freeze or crash occurred. (Just for clarity, Wi-Fi is also turned permanently off for this desktop.)
So, I cannot replicate whatever is causing the problem for you; the "evidence" suggests it may not be the loss of internet.
I think you may need to create a Support Ticket to fully ascertain what is causing this for you. Click on the Support header in any forum page, follow carefully through each page you see, always choosing the option to Ask Support or Email Support (often at the foot of a page). Clearly, you are unlikely to receive any response until the New Year, unfortunately.
After a good and correct answer from Jeff, I have another question. Are you working from Microft OneDrive? If so, this is probably your problem. Close it.
It is best to work from your internal hard drives.