Hi @jayden_gould,
This is because the compute is an atom style compute that produces a per-atom vector. You can’t just add it to your thermo output which expects scalar values.
The compute values need to be invoked in order to be computed and accessed by variables or fixes. I suggest you read the compute and how-to output doc pages in order to better understand when and how to use compute commands.
Your code is a bit hard to read by the way. Please use triple backtick ``` before and after it. See the guidelines post. Without more elements on the rest of your script, it is a bit hard to know if things go wrong elsewhere. A common way of going around compute that are not current is to put some run 0 commands to force the invocation of the compute using intermediate fixes or variables.
Some major changes have been taking place between those two version. 18 month is quite long in LAMMPS development time, so bugs and changes might change the behavior here. You can probably compile newer versions of lammps as a user on your HPC cluster. There should be a helpdesk to help you do that and tell you how to load the proper compilation environment.