I have been struggling since Saturday with data issues on my OP7P after upgrading to Oxygen OS 10.
With Google Fi, I was able to activate the SIM in OOS 10, but the mobile data would stop working. It would work for a little while, but then I would get an exclamation mark on the signal bar and no data services would work. Reactivating the SIM by clearing the storage and cache for the Fi application would work temporarily, but the issue will just happen again. If you are on WiFi, you will not get an exclamation mark and no data services. It only appears when not connected to WiFi.
For Visible, the phone sees that a SIM has been inserted and after opening/authenticating in the Visible application, you will get a message that says it needs to check them SIM. After hitting OK, you get prompted to give permission to the application to make and receive phone calls. After that, nothing happens. The SIM never activates and service is not available.
In both instances, Google Fi and Visible support were not able to figure out how to get their respective services working on Oxygen OS 10. I reverted back to Oxygen OS 9.5.13 (last revision of OOS 9) and both services work flawlessly. My hunch is that this is a problem on OnePlus' side, considering it is happening with both providers, but either way, I hope this gets fixed because it sucks not being able to upgrade.