if your phone was bought outside of Canada (and the phone wasn’t destined for Canadian market), it is a common issue. Koodo MMS server might not support the device. More information could be found here https://www.koodomobile.com/en/help/picturemessagingchanges
I would review this thread, and some of the other links to other posts here. Some folks have gotten MMS to work with an MMS change or tweak. YMMV but it might be worth giving it a try
UMIDIGI is a hit or miss OEM. They’re great for budget options, but aren’t officially in Canada, so support is limited. Not sure what’s going on, but of recent years, there’s been increasing issues it seems with phones not typically sold in Canada. I mean, before you always had to check for compatibility, but it should have worked if it had the required frequency bands. I’ve used Xiaomi phones I bought from AliExpress and GeekBuying etc before and never had issues with the global versions. You might be out of luck if the suggestion by Dennis doesnt work.