Something is way off with your procedure. Pyrocat-HD is an excellent developer for expansion. 24 minutes of development at the 2:2:100 mixture with TRI-X should give you negatives that would be so contrasty they would be unprintable with silver printing. The CI would be well over 1.0, even with the very flat circumstances you describe.

For example, some recent tests I did show the following CI (contrast index) for Pyrocat 2:2:100 and TRI-X film, with develoment in tubes at 70F.

Development Time Contrast Index
6 minutes .55
8 minutes .65
10 minutes .80
14 minutes .90
20 minutes .98

Since a CI of just slightly over .50 would be considered normal for silver gelatin printing you can see how much room for expansion there would be Pyrocat-HD and the 2:2:100 dilution.

Based on your description of very thin negatives I suspect that you did not give enough expoosure, or your negatives suffered from reciprocity failure. There is simply no way in the world a properely exposed negative developed for 24 minutes in Pyrocat-HD could be thin. In fact, it would be so dense and contrasty it would be difficult to make a good print with it even with a process like salted paper that requires an extremely contrasty negative.

Of course there is always the possibililty that there is something wrong with your stock solutions, or that the working solution was not mixed correctly.