Two more points about this brand…
Most of their motion sensors have an obvious looking “tamper“ button. That’s not the one you want to press during inclusion/exclusion.
Instead, there’s a pinhole that you have to insert a pin or toothpick into and press down. So there’s that.
Second, if you have paid the license fee for the third-party Rboy apps code library, they have a DTH for the monoprice sensors which does seem to be working with the new app. Rboy has a lot of different code, both device handlers and smart apps, and there’s a single one time fee that gives you access to everything.
Normally people only need to do that if there are some advanced features that they want access to, it’s pretty sophisticated code. But since you said you had a significant investment in your existing devices, it might be worth it to you to get them working.
Here’s a discussion thread about it. He doesn’t say there that it’s paid code, but it is. The library is very popular with people looking for those kinds of advanced features. @rboy also gives a lot of free advice in this forum. so you might at least ask him if the monoprice Devices that you have (again, he will need the model numbers) Will work with the current app and the V3 hub with his code or not. See the following thread:
[RELEASE] Official Monoprice Motion Sensor with Temperature, Tamper and Battery Device Handler