Quote Originally Posted by Jim Noel View Post
Fix longer, and agitate while in the fixer. Or use a stronger dilution of fixer. If these are fiber based prints, they may take 5 -10 minutes to fix completely. It is necessary to agitate the prints occasionally while fixing.
These times are appropriate for sodium thiosulfate fixers; ammonium thiosulfate fixers are typically quicker than this.

The be sure to wash sufficiently. If you use a washing aid, 10 minutes is enough.If not, 30 minutes is usually recommended.
This sounds like a regimen for fiber-based (FB) papers. For RC papers, washing times can be shorter -- recommendations I've seen range from 2 to 5 minutes, with no wash aid required.