with iron jetpacks and hammerLib installed
the iron jetpaks Items fail to load

BlakeBr0/IronJetpacks#78

SolarFluxReborn-1.19.2-19.3.10
HammerLib-1.19.2-19.3.73

I would suggest isolating this issue into a separate modpack with IronJetpacks and HammerLib, and see what happens.
There is no useful information that can be used to fix this issue so far.