Sonos speakers out of sync since latest update

Hi team, long time reader, first time poster ;)

I've got 12 Sonos' in my house and love them. One thing I've noticed with the latest update (Version: 9.0 (build 44254230)) is that there is a very slight delay (noticeable to me, but not to my better half) when I'm grouping music between a Connect/Connect:Amp and my other speakers (such as a Play:1 or PlayBar+Sub). My living room is quite large, such that one half is a Playbar+Sub and the other half a Connect:Amp - when I group these two rooms for the kids there's a subtle delay, particularly noticeable with the Sub. When I group multiple Play:1's (for example, 2 sets of paired speakers) then there is no delay. I stream my music from Spotify.

I've submitted my diagnostics: 1165078852

Just so you are also aware, I've actually disabled the WiFi on most speakers - I've CAT6'd the whole house and all except one speaker is wired (therefore two speakers have their wifi enabled).

Please let me know if there's anything I should try.

Thanks guys!