Why is my LHS tensioner racked and RHS OK?

See attached. Rhs I can move the guide back and forth, LHS it's right tight, can even put the install clip back.

...

...

Rotate your engine, your loose side should tighten and the other side relax, it can depend where the cam lobes are in relation to the valve spring. The springs can put pressure on the lobes causing it to load the cam in one direction making the chain tighter than the other side which may be past a cam lobes high point and not placing any tension on the chain. I'd start with this then you can look at other possibilities.

For the future of mankind: my tensioner arms were on backwards - the witness marks on my old pivots fooled me into thinking they rode in a different orientation upon trial fitting. I swapped them side to side and it's OK. Lito helped me figure it out!

The arms were from Ford Racing's kit and had no identifying markings.

Glad you caught it and well done Lito!

Once again, Lito is THE MAN! Glad y'all got it figured out.