Since you are using blix, not bleach & fix, this may not be appropriate, but the bleach step needs oxidation. Has something to do with turning ironoxide into trioxide, I think. Anyway I wonder if your blix requires healthy, oxidyzing, agitation.
Yep I think it did - I gave it some good agitation and a bit of a stir before pouring into the tank. Ta!

I've heard this about combined Bleach-fix before ... that it tends to leave a sliver residue.... but no one can ever explain where the silver would come from - or why it would be more prevalent with a combined "blix" than separates ( Blix
form the data sheets) contains a ferric compound - no silver whatsoever.

Careful with shortstop - Tetenal and Photocolor both advise against its use between color developer and blix. I do NOT use it - nor a water rinse.
Do you know why they advise against it? I did do it actually, but then my kit said that it could be done with either stopbath or water rinse. I take it this is something that varies between the various manufacturers?

Out of interest, did you try re-blixing the film, and if so, did it work?

Cheers, Bob.

P.S. Last time I did C41 (my 6th roll ever), I managed to get Blix and Dev swapped around... Those negs were pretty dense too ...
I tried to rebleach one negative that had been developed. The only problem I had here was that I was running out of blix so I mixed the solution as best as I could and left it in there for a period, while agitating. This did seem to imporve the density problem, although I would need to mix up a proper quantity for it to be properly effective.

I know that I didn't mix up the dev and blix cos I made sure they were separated in order for that reason (I've done other similar things where the order/process/control are just as important - learnt my mistakes there, but they were a lot more costly cos it was carbon fibre composite bodyworks!) This is only my third roll of any sort so I'm pretty happy that it came out well. My main reason for doing this is to make cross processing cheaper for mylself - especially on medium format (the only place I know of charge a lot for medium format anyway, and then extra for XP).

I also tried developing a new film from scratch, and used a tip I read elsewhere too. I developed for only 2 mins 45 secs at 38deg, with slightly dif agitation to what I previously used, then stop bath, and blix for about 10 mins (instead of recommended 6). Then I tried the Ilford suggested rinse at the end, cos I don't like wasting that much water!