primeapebarrel.lua line 154 says:
MakeLargeBurnable(inst)
However, it does not make the instance a propagator by calling MakeLargePropagator(inst).
This allows them to be ignitable with a torch and spontaneously combust during summer. However, they will neither catch fire from surrounding fires, nor ignite the surrounding flammable objects when on fire.
Steps to Reproduce
Does not catch fire: 1. Build or find a Prime Ape hut. 2. Place a campfire as close as possible to it. 3. Fuel the fire to its maximum. Expected: It catches on fire. Actual: Nothing happens. Does not spread file: 1. Build or find a prime ape hut. 2. Surround it with flammable objects as close as possible. 3. Ignite the hut with a torch. Expected: Surrounding flammables catch on fire. Actual: Nothing happens.
Does not catch fire: 1. Build or find a Prime Ape hut. 2. Place a campfire as close as possible to it. 3. Fuel the fire to its maximum. Expected: It catches on fire. Actual: Nothing happens. Does not spread file: 1. Build or find a prime ape hut. 2. Surround it with flammable objects as close as possible. 3. Ignite the hut with a torch. Expected: Surrounding flammables catch on fire. Actual: Nothing happens.
A developer has marked this issue as fixed. This means that the issue has been addressed in the current development build and will likely be in the next update.