1980s international cabover starting problems

We use our old road trucks in our yard. One truck in particular will start fairly easy in the cold when the block heater is plugged in. It will run and warm up for about 30 minutes before being backed into the plant to pull loads out. It's shut down in the plant due to ventilation. The plant is low 70s and extremely humid because of steam used to cure concrete. After being off for about 30 minutes, it will not start inaide. It cranks exactly like it should but is not getting fuel. We have replaced the filter right there in case of gelling but the fuel isn't gelled at all. It has to be pulled out from the plant. It's plugged in and a few hours later it will start with no problems. Can anyone point us to why it will start and run in the cold but won't restart in the heated bay, but when taken outside for a few hours it will start and run with no issues