V-Core 3 Rapido UHF + LGX Lite. Constant issues with filament not extruding/getting stuck in hotend.

So far I have took the printhead apart multiple number of times (at least 10 times), to fix this issue.
It happens almost each time I want to switch out the filament..
It keeps getting stuck right at the opening of the hotend, where the ptfe tube meets the hotend.. It does not help pushing filament through, it is is still stuck. It happens a lot and I'm getting very tired of it. Can anybody help me to fix this issue?