IIRC, I had to turn off the simple references setting in the project and then go through third-party modules and fully qualify classes, etc: e.g. Dictionary -> Xojo.Core.Dictionary
I turned off the Simple References and fully resolved everything. That worked and wasn’t all that much work. It’ll probably make some things easier later on.
You will only see this setting when opening an older iOS project (pre-2020r2), but to change this setting look at the Shared Build Settings in the Navigator: