Can't set output as intermediate data

[RobBlash]

I have a model where I can't set some of my outputs as intermediate data. I have some intermediate data in the model, that's great, but I have more data that needs to be checked as intermediate so it gets deleted once the model has run. One of those can be set to managed, but intermediate is grayed out. I just want it to be intermediate, not managed. There's no documentation (that I can find) that will explain what restricts an output from being called intermediate. Any insight would be greatly appreciated before I lose my mind.

[AndresCastillo]

Thank you @curtvprice ,

This makes a lot of sense.

I notice a scenario in which there are additional things that would affect the ability to set the element to intermediate data.

Even a data element is 'truly intermeditate' as you have described above, if that intermediate element is connected downstream to both a tool that 'consumes' the dataset, and a tool that 'creates a layer view that points to the dataset', the option to set intermediate disappears.

In my case, the output to the 'Copy Features' output was not able to be set as intermediate, even though it served as input to both the 'Table to Excel' (consumes the data) and 'Select Layer By Attribute' (makes a view of the data) GP tools.

See the attached pictures of how the 'set intermediate' option appears once the downstream links are removed to the 'Select Layer By Attribute' gp tools.
@RobBlash 

According to your clip 2 above, that seems to be what is going on.

@DanPatterson_Retired  

I am able to set variable as intermediate in ArcGIS Pro 2.8.8 still.