ive encountered this same issue. im running the following mods on my server:

Map: Tunguska

Extinction Core
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=817096835
Builder's Helmet
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=756389708
Uber Crafter
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=752691369
Castles, Keeps, and Forts Architecture
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=764755314
GateMod Remake
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=817961155
Big Walls
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=541612317

Hover Platforms
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=762778283
Aviary Structures
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=802922362
ecoTrees LITE
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=795044845
Upgrade Station
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=821530042
Kibble Table
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=774762563
Weapons+
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=812639416

Armor+
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=764792033
3's Scorched Earth Stacks
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=758535617
Death Recovery Mod
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=751991809
Omnicular
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=538827119
Awesome Teleporters
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=889745138

I had this issue as well and Extinction Core causes the issue. I don't know why, but Extinction Core overrides the vanilla Industrial Forge with its own custom version that does not unlock the UC Industrial Forge.

If you are having that issue then simply make a custom engram override for this forge that removes the pre-requisites, info on how to do this is readily available.