Project--units not showing up for one of the compared product systems

Question

I am comparing multiple product systems in a project, but for one of them, I can edit the amount but not the unit. So every other product system is standardized to 1.0t of product, but one (I'll call it A) shows up only as 1.0 with no units. When I try to add or type a unit it doesn't work, no units show up in a drop-down menu. I have tried and failed to find any other difference between A's product system, processes, and flows compared to the other product systems that might explain this but can't find any.

Thank you!

Edited with screenshots.

The missing unit in the project setup tab:

Units in the product system (this is the same across all the product systems compared):

Comments

Thank you for your response! I edited in screenshots of what's going on, I believe it is a valid product system.

Answer 1

I can't believe this worked but I just added the product system again and it worked fine.

Comments

If it was removed because of a script I applied, I managed to write and apply the script completely without awareness. My theory is I mis-clicked something when creating the product system and never had an opportunity to un-click it, but I truly don't know.

Answer 2

Thank you - can you make a validation of the database (right-click, validate). Just for my understanding, these are different product systems, right?

Comments

Thank you for your time!

They are 4 different product systems, 4 different methods to sequester CO2. I clicked 'validate' on the database and for my project it says:

"invalid reference to unit=0 property=0 in variant @716578", and I'm not sure what that means.

There are also a lot of "<process name> internal ID of exchange (<number>) is larger than last-internal ID (0) of process", but I don't know if that is relevant since I don't think I use the processes with the error.