I have a Content Type defined in our tenant's Content Type Hub. This CT is based on the "Event" CT which some fields added to support it's use for a Leave Request app I'm building. There are some columns that I want to only be available/editable via PowerApps and Flow, so I made them "Hidden" in the CT. I created it yesterday afternoon, so I know it's fully syndicated by now.
In one of our Site Collections, I can view the Site Content Types and it shows up there with all of the columns that are shown in the Content Type Hub. Great! Next, I create a new ("modern") List and add that content type to it. This is where the weirdness starts. In the List Settings, I don't see any of the Hidden columns. From the Settings, if I click the CT name, no hidden columns. If I then click the Parent CT (so, the copy that exists at the site collection level), there are the hidden columns.
Thinking this was some kind of syndication issue, I went to the Content Type Hub and created a List there and added the CT to it - the same thing happens! Further thinking this may be a "modern vs classic" issue, I created a Custom List "App" and applied the CT to it - same thing. This is very frustrating. As our goal is to create a "standard" Leave Request/Approval process that can be rolled out to various departments and groups having a standard and consistent Content Type is a must. I suppose another approach is to create a site script that creates the list when/where we need it, but if we need to change something in that list, without the syndication function, we'd need to make that change in each site/list individually.
@null null It is a known issue. It is reported since a year or just over a year and you can find many posts everywhere related to same subject.
If we make a column hidden in site content type/content type hub content types then it will not be visible
In list settings
In list content type
In list views.
I am not sure about search index. I will do little bit of research and will update this thread. Mostly they should be available in search, but it may not be. Will give you more details on that sooner. Hope Microsoft fix this issue.