Trouble with Fuji Hunt C41 Bleach

I have at last used up all my 'Kodak Flexicolor III' C41 bleach, Parts A and B but still have Starter. Some years ago I was GIVEN by a local newspaper 2x 5 litre lots Fuji Hunt C41 NEGACOLOR RA Bleach and a 500ml pack of Ultra Negacolor Bleach Starter. I read the instructions on the 5 Litre Bleach Replenisher pack for 1 litre 'working solution' and divided it by half to make 500mls -- as I poured in the 'Starter' there was a Green Explosion !! It all Fizzed over my measuring cylinder into my darkroom sink and up the wall ! I never had THAT effect with the KODAK !! So I tried another mix-- this time i added some Water to Bleach Rep and Diluted the Starter THEN carefully poured it in and it tried to fizz again but I was lucky!
I processed an Ilford XP2 Super 400 C41 film and it seemed to have no retained silver . Has anyone else had this with Fuji Hunt Chemistry ? I admit it was OLD by now but I had never used it .

That is frighteneing. One more reason to start using googles.

You may have mixed up products.
I have not got the old data sheets at hand, but at the moment they offer two different C41 bleach replenishers. And the RA version does NOT have a starter, whereas the standard version has.

(Your result is surprising nevertheless.)

Typical C-41 bleach is somewhat acidic (pH ~ 4.3), and the bleaching&re-oxygenation process raises its pH. Therefore I would expect the bleach replenisher to be even more acidic, and the bleach starter would be somewhat alkaline. If Fuji uses some carbonate in their bleach starter (couldn't find an MSDS, so IDK for sure), then you would see this kind of fizzling. This could also happen if the bleach starter contained hydroxide and got turned into carbonate from aerial CO2. Whatever happened, I would certainly assume, that the bleach starter contained the compound which fizzled, not the bleach replenisher.

You could try the following: Mix the whole amount of starter with only some of the required water into a container which can hold much more than the total amount. Slowly add bleach replenisher until fizzling has subsided, then add the remaining amount of water.