Sounds like you are generally proceeding through things logically. The fact that you get temporary relief seems significant to me. Only thing is point number 3. It looks to me like you may have dropped the ball here. As the improvements were dramatic even if just temporary maybe you need to unpackage this. Did you combine both lateral glides + neural mobs from the start? If so that wasn’t very logical. Did you only do the combination of lateral glides + neural mobs once? From what you have written it isn't clear if it was the lateral glides or the neural mob that improved matters (or if it was both). Maybe you should go back to just applying the lateral glides, see if you get an improvement just with this and apply a few times. If you don't get an immediate response then you know that probably wasn't easing technique. Then you could work on just applying the neural mob, but do it several times and do it yourself rather than self stretches. In short: refine your detective work so you can identify the technique that may likely provide the most benefit on reapplication and progression.
A couple of things to consider:
Do you think the has an inflammatory component (Go back to your 24hr behaviour and irriatbility). If yes this may be why it isn't settling. The mechanical therapy is providing a temporary space for the nn root but on release of the technique several hours/day or two later their is mechanical irritation of the inflamed nn root.
Are you sure the paraesthesia and numbness is due to nerve conduction problems? the positive ULTT with radial bias would suggest that. However think about the dermatome. Does this match? There is no frank weakness, Is the numbness both subjective and objective? If only subjective could it be epiphenomena eg. trigger point or autonomic as in T4 syndrome? If so the temporary response to treatment might be more due to the pain gate mechanism rather than mechanical effects. So why don’t you go back and really confirm your neuro signs
Do we have an opinion from a MSK physiotherapist who may be more on to it than me?