The Space Matter Refineries are getting stuck because they can not output if only 1 output of the refinery is connected to a pipe.
When both are connected then everything works fine.

I think the problem is that the Crude Oil duplication recipe of the Space Matter Refineries is outputting crude oil at a temperature of 60° and with 10% chance crude oil at a temperature of 25°. Maybe change the temperature to be the same?

Usually, they mix fine but for some reason, if only 1 output of the refinery is connected, the refinery gets stuck.

I just had a crash but I dont know exactly what caused it because I went afk for a bit:

Error MainLoop.cpp:1207: Exception at tick 8782390: The mod Spaceblock (0.3.7) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event spaceblock::on_research_finished (ID 18)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
spaceblock/control.lua:83: in function 'RefreshAssemblers'
spaceblock/control.lua:106: in function 'y'
spaceblock/lib/lib_control.lua:284: in function <spaceblock/lib/lib_control.lua:284>
stack traceback:
[C]: in function 'index'
__spaceblock/control.lua:83: in function 'RefreshAssemblers'
spaceblock/control.lua:106: in function 'y'
spaceblock/lib/lib_control.lua:284: in function <spaceblock/lib/lib_control.lua:284>

Factorio Version Factorio 0.18.36 (build 53200, win64, steam)

After posting this I saw that the bug with the research was already reported. ("Error finishing Minining Productivity 2")

Sorry about that.