Best guess for delamination is poor adhesion, due to contaminated surface, or bad glue procedure /conditions. Add flex and off it came. A section of one of the carbon fiber hulls delaminated on my trimaran. I talked to a highly skilled fiberglass, independent repair person (boat wright / ship wright) who solved my problem. Ask around your area if they have time to do some creative work.
Maybe they could seal it similar to vacuum bagging and see whether it would hold a vacuum. They are very creative. Might need to remove some trim and seal the underlying edges to get the vacuum needed. If so then, pull in low vicosity, slow cure epoxy from one end and out the other. Use mold release (aka wax) to prevent epoxy from sticking on outside visible surfaces. Or creative use of sealing tape.
