Font Remix Tools Plugin - Trouble

Every time I try to run font remix tools (tuner or scaler) I get this error message>> Some layers are not compatible so only slanting is available. I have setup multiple masters with different weights and I don’t have anything that looks incompatible. No red layers or warning signals or anything like that so wondering if you guys can help! My goal is to run “scaler or tuner” to help with creating a lighter version of my font to interpolate. Thanks in advance for any help.

Which app version are you using? And which plug-in version?