Without deep diving, this currently cannot be accomplished and is an existing ER.
I would suggest submitting the file to your local support resource for further investigation at which time you can be added to the existing ER.
Ive had it to it before, its just not working on the particular assembly. see here is another assembly it pulls in the miter angles from. Miter Angle 1 & Miter Angle 2 are selectable columns and data you can pull into cut lists
I only can do an assumption what could be happend here.
How are those frame elements created?
Are the ends possibly trimmed rather than created in native frame manner?
If trimmed You never ever will get any miter angles.