Depending on the time period, some adhesives were sensitive to moisture and humidity and delamination has occurred. I did a report up about a year ago for a church where the glulam beams had delaminated due to an improved mechanical system and improved windows and doors. The problem was humidity.
It was recommended to replace beams. Because the splits were so fine, in most cases, it was not possible to inject epoxy into the splits with the problem being the existing glueline. The owner opted for providing intermediate supports to minimise the span.
Homes have changed and people are spending more time at home and, in general, generate more humidity. This coupled with an improvement in sealing and insulating homes has caused some new problems that didn't exist two decades ago.
Dik