@Petri @mhalttu You may want to take a look at this thread, it seems like a few people have had very similar issues with sound playing briefly during the start of battles specifically on Android devices, likely starting with Version 18. I merged a few bug reports together.
I’m not sure if this is related to [KNOWN ISSUE] Version 18 Sound Issues (Please report any here!) or the building upgrade sound fixes from 18.0.1, or just something new. Feel free to merge elsewhere if applicable, thanks!