Wow! This is different. I myself have brought my level to the edge of levelling up so many time, just to keep it there long enough (sometimes for as much as 2 days) in order to have 6 consecutive hits against a stronger Titan the moment he appears. This way, alliance energy starts rebuilding right away, and we get the maximum hits possible on a Titan - without the benefit of alliance energy flasks, of course. Never have I been levelled-up while not on.
That said, I did notice 1 time before when I was playing, levelled-up, and got no notification of having levelled-up, received no free summon token, and no particular items either. It may have been at the same 14->15 stage… …I can’t recall for sure. All I can say is: I haven’t seen this happen again since [ and I’m at level 26 now ].
I never considered the idea of reporting the issue. In the grand scheme of things, I don’t think it would really make a difference anyway. I have found out since that odds are so heavily against us (or at least me), that an extra token is not likely to have made 1 bit of difference to my play. I recently spent $ to get gems and attempt to get a 4 or 5* hero during the last event (the Pirates), using the 10X summons, and got none! Just got a whole bunch of 3* hero duplicates, all of which I already had.
Also, in my alliance, some of us started saving the tokens collected from quests, chest missions and levelling up, collecting on only the actual “free” summon on a daily basis. I managed to resist the temptation of using those tokens until I had accumulated 30 of them. When I finally used them, only got 1 and 2* heroes or troops. Not a single 3* hero or troop!
I’m not telling you you shouldn’t report the bug. Somebody probably should. I’m just giving you a glimpse of my experience in this game that might help you decide if it is worth your time and effort for the sake of: 1 token, world/raid/alliance energy refills (that are usually fully refilled in 12 hours or less anyway), and a couple of gems.
Just my 2 cents worth.
Whatever you decide to do: Be sure to remember to have fun and enjoy yourself.