Hi Jeff,
My apologies for the confusion that the documentation may have caused. This
documentation only pertains that the Label can be used as filter. However, the values used to filter the said field is done differently and is discussed more in details in this
guide.
For your second concern, I have tried replicating the issue, however, I did not encounter the same results with what you encountered. I was able to encounter the error ERROR_GETTING_RESPONSE_FROM_BACKEND, since it recognized my predicate as an invalid string filter. Could you confirm if you are using the same AWQL statement as the one below?
"SELECT CampaignId, Cost, Labels, CampaignStatus, BudgetId, LabelIds FROM CAMPAIGN_PERFORMANCE_REPORT WHERE Labels CONTAINS_ANY ['Video']"
If yes, let me know if you still encounter the 500 error so I could investigate this further.