I use the visualization tool to edit the custom properties of the parts from the assembly. The advantage is the speed, and to have the visual of the room next to it.
However, when I register my assembly, the modifications of the parts are not taken into account, except for rare exceptions.
For your click on "this answer solved my problem" it's up to you, the problem is not solved but Solidworks doesn't seem to be in a hurry to find a solution. However, this will prevent you from being harassed by LYNKOA who doesn't really like unresolved discussions.
I can't even find the request for revision on this subject anymore. (SR and not KB as mentioned in my previous message)
A very small lead though, (SolidWorks 2020 help) but I don't really believe in it....
Reply to the ticket I started at the same time as this topic:
According to SOLIDWORKS' feedback, this is indeed a bug reported in 2017 and marked resolved for the 2022 version of SOLIDWORKS, (SPR: 1134878 - 'It is not possible to keep the changing a custom property in column of Assembly Visualization')
As specified in the developer's answer, there will be no other workarounds today than two modifying the property directly in the room