Command line building gettings stuck on "Unloading 0 Serialized Asset files" loop.

I am building a Unity project from the command line but it seems that the process is stuck in a loop of:

 [16:16:48][Step 1/3] Unloading 0 Unused Serialized files (Serialized files now loaded: 0)
 [16:16:48][Step 1/3] System memory in use before: 2.00 GB.
 [16:16:48][Step 1/3] System memory in use after: 2.00 GB.
 [16:16:48][Step 1/3] 
 [16:16:48][Step 1/3] Unloading 0 unused Assets to reduce memory usage. Loaded Objects now: 9345.
 [16:16:48][Step 1/3] Total: 6.062036 ms (FindLiveObjects: 0.649146 ms CreateObjectMapping: 0.341894 ms MarkObjects: 5.059497 ms  DeleteObjects: 0.010537 ms)
 [16:16:48][Step 1/3] 
 [16:17:26][Step 1/3] Unloading 0 Unused Serialized files (Serialized files now loaded: 0)
 [16:17:26][Step 1/3] System memory in use before: 2.05 GB.
 [16:17:26][Step 1/3] System memory in use after: 2.05 GB.
 [16:17:26][Step 1/3] 
 [16:17:26][Step 1/3] Unloading 0 unused Assets to reduce memory usage. Loaded Objects now: 9345.
 [16:17:26][Step 1/3] Total: 6.019810 ms (FindLiveObjects: 0.639635 ms CreateObjectMapping: 0.329650 ms MarkObjects: 5.037901 ms  DeleteObjects: 0.011509 ms)
 [16:17:26][Step 1/3] 
 [16:18:04][Step 1/3] Unloading 0 Unused Serialized files (Serialized files now loaded: 0)
 [16:18:04][Step 1/3] System memory in use before: 2.10 GB.
 [16:18:04][Step 1/3] System memory in use after: 2.10 GB.

And it keeps going higher.

What seems to be the problem here?