Hi there !
I'm not sure if it's a bug or not but we played a fair amount of games, most of them are now done in endless and with friends we made a statement.
When we are looking for specifics (and it is even worse when we are looking for 1 or 2 gears) gears or techniques (yes it occurs for techniques too even if we usually are taking whatever it's offered and basically don't look for one in particular) we can reroll and level up as much as we can we sometimes NEVER gets them, even in games that we go to level 140+.
So knowing that we tried to play more games with that in mind and it appears that we have a restricted pool of gears (cause like i said we don't focus that much on techniques so i can't tell much about it) and no matter what we can do (banishing, rerolling, replacing existing gears etc...) there is always few gears that we can't get no matters if it's synergy or not.
We perfectly knows that RNG can suck sometimes but games with at least all members 100+ facing the same issue seems hard to explain when it occurs so often. We played a lot of games with friends and it's always the same, we just can adjust our techniques to fit our gears since other side is totally impossible and it's not a good design.
So, for all of those things i am rather convinced it's a bug instead of a real huge lack of luck.
Maybe we definitely miss something or is there even a hidden rule we don't get but that's what is happening for all of our group of friends.
Thanks.