We have a problem with poorly made pipe fittings, incorrect taper etc. I think the items sent to Latin America are mostly seconds etc, it is always the same when purchasing them. The only way to even attempt to stop leaks is to use lots and lots of wraps of tape, would liquid Teflon work better in this situation? (BTW blue loctite works well to stop leaks, but is semi permanent).
Apply PTFE thread tape first, then add pipe thread sealant to the male fitting on top of the tape. If you're still having issues, also apply pipe thread sealant to the female fitting, and press into the threads with your finger, removing as much as possible before threading the pipe together.
Instead of using a non-hardening pipe thread sealant, you can try a soft or a hard set seals instead if the joint still leaks.
I would use RTV silicone on the thread. And before I hear from doubters, let me say that when I was still working, I used this type silicone on any thread that would leak that could not be sealed with any other means. If the pipe fittings were mostly imports I would use this silicone on the whole job with no leaks. Use it alone with no teflon tape of any thing else. Just make sure that the pipe thread is free of oils and debris and give it a day or 2 to set up, if you can.