Hi David nice to meet you.
I use wall hangers in my home and currently have a couple dozen gracing my walls. I also keep my home 45 - 50% RH year round as measured with annually calibrated lab quality mechanical hygrometer(s). Digital hygrometers are inherently inaccurate, drift in time and have an issue with a sweet spot where they may be accurate and they can be 15% off in other areas.
So wall hangers are not a bad idea and I end up playing more not having to deal with cases and such.
Sounds to me since there is a loose fret right out of the shop where it was dressed that the fret dresser missed something important. Checking and glueing any suspect frets is key and has to be done prior to leveling and such.
If we had this guitar in our shop and we don't want it

no offense we are always booked way out on fret work we would glue them all and start over. The fret plane is very sensitive to errors and the only way to know that the fret plane is really level is to read the bluing (ink) we work to eliminate when pursuing a level set. We would be interested in matching the RH of your situation too so as to not have the set-up change as it sound like it has too.
Lots of shops can do good fret work but in my experience the shops who do not treat the fret plane as a whole and spot level cannot provide the results that those who do treat the plane as a while can. If you have to have this redone might be prudent to ask a provider about their process before committing. Not dissing the Luthier you used but handing a fret job to a client with a loose fret does not inspire confidence.