labelField not defined
It seems that a labelField is not being defined in the XML that defines the data structure in Civirules. This came to light via an issue with the Fast Action Links extension, which prevents the rule title being displayed in a drop down list of available rules.
The issue is described here: https://github.com/MegaphoneJon/com.megaphonetech.fastactionlinks/issues/7#issuecomment-1008690610
According to the FAL developer, writes:
I believe older versions of Civi, where data structure was less consistent, worked around this with some "magic" to guess the label field, but now it must be defined explicitly. To replicate this issue, go to API Explorer and do the getlist action with nothing else defined for the CiviRuleRule entity, and compare that to, say, getlist for Contact or ContributionPage entity to see what I mean.