Alter Field tool missing option to change non-Null to Null field

[AnnaSan1]

I am pretty sure the Alter Field tool had the ability to switch a field from Non-null to Allow Null field property in the past. But the check box for it is now missing. I am using  version Pro 2.2.3. Where did it go? Any help is appreciated. I don't want to have to reconstruct my feature class if I don't have to.

Thank you,

[DanPatterson_Retired]

according to the help, the table has to be empty to change that property

Alter Field—Data Management toolbox | ArcGIS Desktop 

[AnnaSan1]

My feature class has no data or records in it. 

[DanPatterson_Retired]

I guess a picture will show what is needed. There is only one field there that is 'nullable'

[AnnaSan1]

Hmm. Odd. It is now showing up after I upgraded to 2.2.4. I still don't know why the checkbox for 'IsNullable ' didn't show up before though. 

Thanks for your help anyway!

[DanPatterson_Retired]

Your image shows nothing selected or input, hence the option wouldn't show.

I did that screen in Pro 2.2.3... and I just updated to 2.2.4 and it is still there.  Not the update, it is a sparse one and not related to your issue.

It wouldn't be there if there were no fields that were nullable like OBJECTID, SHAPE and its incarnates.

If there is a nullable field it appears, but disappears if you select a forbidden field.