Due to how the source engine handles particles, there appears to be a conflict with the Hazard Course mod that causes the MMod fire effects to no longer show up. As someone who knows very little about source engine modding, I believe this is caused by both mods containing a "particle_manifest.txt" file.

This issue is very inconsistent in it's appearance - it wasn't working until I moved the Hazard Course files out of my custom directory and renamed this mod's file to "!-BlackMesaPEP.vpk", but it kept working after I moved Hazard Course back in and reverted the rename - but I am fairly sure that these are the two mods involved in this conflict. The only other mod containing the manifest file is BCME Revised, but it seems to be a copy of the files included in Hazard Course, and I'm fairly certain the VPK files take priority over loose files.