TLoftus, have you tried unpairing or deleting ONLY the data from the planned workout, and then pairing the good data with it? It won’t pair if there’s data already in there. To delete the data from the workout, open it in summary view, click on Files at the top right, and then ‘delete’ under the filename.
Another thing you could try (if you’re able at your subscription level) is copying the planned workout and pasting it on a future date, deleting the ‘bad’ one, moving the one you just copied to the relevant day, and then pairing the good data with it.