This is now the third time I've gotten this error while customizing a screen.
In this scenario, I added two date functions to the screen's load actions: one to get yesterday's date and one to get the date from 5 days ago. And then I added view filters to a grid that use those shared results.
Afterword I clicked save and got the following pop-up:
Please try again. If the problem persists, sign out, sign in, and try again.
If the problem remains, please contact your account administrator Method Technical Support or Method Support (support@method.me).
The screen is now unusable; and what's worse, the only other version of the screen is also having this error (and thus also unusable).
And yes, I signed out and signed back in, and it doesn't do anything.