L4D1 common infected not showing on L4D1 maps
 

There is a weird issue on my servers. L4D1 maps don't have the l4d1 commons but only the l4d2 default. Only happens with commons, special infected work as intented.

I tested on singleplayer and other servers and they show up there, so it's a problem with this particular server. What could be causing this?

I had a similar problem before in which l4d1 population was forced to be the only one without l4d2 in every map. It was caused by the custom map the hive which I had to remove to fix the issue. But it's weird that a a custom map would now force something like this in this case.

I remember l4d1 skins being there when the update came out, this problem only started recently.