Just to clarify, one has requested the jump seat, you have granted it, but inevitably one gets a seat in the back. Would you expect that person to come and say thank-you, send you an email under those circumstances? I wouldn't.
Personally I think if you "use" the jump seat, then thanks would be expected and forthcoming, but if you were allocated a seat down the back, then the jump seat was just a strategy that one would use to make sure you got a priority you may not have had.
For sure, it's acknowledged that you granted the jump seat but if one didn't use it because of the loads, then why? Also by the time one gets to leave the aircraft it is usually chaos as the other passengers are pushing past you if you dally to exchange pleasantries.
One other issue, is that our Employer sometimes changes a schedule and its not timely nor possible to either cancel or advise you that one can't connect. Freighter guys are the worst for this, through no fault of their own, so take that into consideration as well, as that might be the reason. It is acknowledged that the multiple
JS appliers are a problem, but it's not always the case.
Keep it up chaps, it's one of the best things we can do for each other.