Well yes, you're right about the Foma films. I'm using Kodak's Flexicolor fixer for C-41, which is really nothing more special than your garden variety rapid fixer. A wet, but undeveloped chip of Foma film clears in no time flat. Perhaps even 30 seconds is overly conservative. I gave a figure of 1 minute to account for more highly diluted fixing baths and/or partial exhaustion. A piece of fogged, but undeveloped, paper with the purple/grey coloration the OP described, will turn white in that fixer almost upon contact. If ten minutes are needed to completely fix out a sheet of paper in ANY rapid fixer, the stuff is near useless and should be discarded.

I'm spoiled rotten by this fixer. It is very fast, and even better, it's cheaper than anything else I can lay my hands on. The PH is about 6.5 at working strength, which makes it nearly neutral, and it washes out quickly. There is no hardener, which is unnecessary for the materials I use most frequently. Enough concentrate to make 5L of film strength working solution can be had for around 5 USD around these parts.