If those NPT hose ends are Chinese made that could be the culprit for sure as I also had experienced recently. Seems to be a common occurance.
Regarding tapered pipe sealant, I use Loctite 569 liquid sealant instead of Teflon tape.
The sealant is easy to use and always provides a first time leak free joint... provided the tapered pipe threads are correctly machined.
Self locking once cured but easy to disassemble if needed and ease of thread clean up. Clear red tinted thick syrup when applied.
The only time I use Teflon tape is on potable water connections but only because I do not know what the Municipal code specifies.
