Hi Johan
I dig the song, as you say, not your normal bag.
(listening on AKG K271 - so not the best I'm afraid) I understand your mix problems, to my ears it's all to do with conflicting frequency bands and postiion in the stereo soundstage, especially in the chorus, the conflict of the organ, rhythm guitar, they sound like they are merging together, then in the instrumental pre chorus it all comes clear when you move the guitars out to the sides a bit.
Personally I'd lose the electric guitar in the verses, and bring in a new instrument verse by verse. just the piano V1, add organ in V2, then electric guitar etc.
I'm surprised you found it difficult because your previous mixes have been pristine. Anyway here's a few ideas....chuck 'em out if you want...
Drums
Snare could do with a bit of verb or subtle echo. Sounds very dry.
Kick could come up tad, maybe tune it to the tonic of the song. I guess it has a comp on it but
Bass Gtr
Can't decide between dbx 160 or transient shaper to add punch.
LVox
A bit more or the echo ( I can hear it ...just) and plate verb
BVox in final Chorus
Maybe 2 or 4 ooohs, would add something different, and a crescendo to the whole thing before the solo piano outro.
You might benefit from either removing an instrument completely giving yourself more room, like the organ, or permanently swing it out a bit further to one side and chop off the offending conflicting freq from the thing nearest it...
Hope it helps...
Rich