Are you actually getting an error message? Or basically you are just seeing inconsistent results?
While I don't use Power BI, if the same query is that inconsistent, it might be worth reaching out to client care to help look into what is happening.
If there is an actual error (particularly one that doesn't give helpful information), then definitely contact client care as they should be able to see more details from their side and can dig a lot deeper into what might be happening.
Someone else here might know Power BI, and be more helpful.. but in any case, good luck!