I did a panel swap a year ago and, making use of materials in the van, I used a short piece of ENT to extend conductors to the panel. I used PVC conduit connectors, which is acceptable by the manufacturers.
This week I added some things and got rid of the ENT. I tugged on it and the ENT cracked off at both connectors. All I can think of is that the solvent cement weakened the ENT. Weird.