This article covers the most common reasons for discrepancies between data you see on YouTube and the results in your Supermetrics reports.
Incompatible fields
YouTube API restricts the types of fields you can pull at the same time. For example, if a query pulls video views and splits them by gender, it'll encounter an incompatible fields error. This happens because views is a video-level metric, while gender is a user-related metric.
Viewer percentage is a metric that a query can split by gender, for example, because it's measured on the user level (rather than the video level).
Read more about YouTube's reporting structure in its documentation.
Video/subscriber count
If you're not using the Channel totals account option, you might encounter discrepancies in your data.
To use the Channel totals account option, select Channel totals in the YouTube channel/video selection instead of All videos, All listed videos, or Top videos.
Using any other settings, or combination of settings, will result in fields having multiplied values for each video listed in the results.
Monetization data
You can only pull monetization data for channels that have monetization enabled on YouTube. Make sure you're eligible for YouTube's partner program and that you've completed all the steps to turn on monetization for your YouTube channel to access monetization metrics.
If you try to pull monetization data for a channel for which monetization isn't turned on, you'll get an error.