Something that I have seen many times, is a Poly Bushed UCA squeaking badly if the sleeve for the bolt sits inside the bushing.
In this situation, the clamping force of the UCA to UCA Mount bolt will compress the bushing and cause contradictory pivoting.
Pivoting of the UCA assembly should be done primarily by the inner metal sleeve in the bushing pivoting inside the bushing. If the sleeve is on the narrow side, the entire bushing housing can/tries to pivot around the entire bushing. This builds up heat and friction and causes that old box spring mattress groan sound.
OP, it may be a good idea to pull the UCA off and make sure the sleeve does not sit inside the bushing ends (too short) - IF it does, you may want to acquire a longer sleeve.
If you notice the sleeve is too short, and want to confirm whether or not it is the issue...you can remove the bushing from the UCA and check for heat/friction marks in the main bushing housing. Typically this will be shown by distorted and shiny surface area (powdercoat will not look right)
If you need any help, we are always here to help.
Good luck.