Before anybody can safely say this is a glitch or malfunction, we need to see the playcheck results.
Posting a screenie of the win doesnt cut it these days, as too many fraudsters have tried to dishonestly claim they hit wins that they actually didnt.
It would be interesting to see playcheck, as the casino/MG are saying it doesnt show on their end and I assume they can see the same as you can see via that method.
It could be the result of corrupt data arriving from the server for the result. Playcheck extended view will show what symbols were really there.
It COULD be a malfunction if the server failed to log this last spin after resolving it.
I recall another
32Red malfunction on GeeGees, where a player held a Disco Ball, and the next spin gave the other two with a nudge, but the HELD Disco ball was replaced by the BAR symbol, even though it was HELD. This was a clear case of slot malfunction, so it CAN happen, even with MGS.
Given all the messing around MGS have been doing, it seems there has been an increase in malfunctions, some of these INTENTIONAL, like the loss of new games for US players, initially dismissed as a "technical glitch", and more recently, the complete disappearance of half a dozen games from my All Slots download lobby
Assuming the OP didn't spin off from this disputed screenshot, here is something they might like to try.
Install 32Red onto a DIFFERENT PC, and THEN re-enter the game, to see if it STILL shows the same error on a clean install. If it does, then this is ON THE SERVER, rather than being a local glitch, such as a corrupted file in the casino software.