I can’t really answer your question do to the way I understand how you applied the Truoil. I have made my 14th bow, all Osage, and have only used Truoil as a finish. After shooting the bows in about 100 shots, I will apply a minimum of 4 coats on,but if patience will allow 5 or 6 coats. I will wait a minimum of 24 hours between coats to make sure that each coat fully cures. If you put 2 coats on to close together, the 2nd coat could impede the 1st coat from curing 100%. Keep in mind no sealer is 100% moisture “proof”, just moisture resistant.
Possibly the type of wood used, and lack of proper curing of sealer could effect the situation, along with a change of weather experienced.