Power Pivot Table fields not refreshing

[SOQLee]

Is there a finite number of measures that can be created in Powerpivot?
I have numerous measures; after refreshing all; some measures disappear from the table fields.
I've tried searching by name under the ALL tab. They are simply gone.
I can see the measure in the Powerpivot Manage screen, but same measure is not listed in the table fields.
Also measure isn't among the manage measure list via ribbon.
I'm using Excel 2016.

 

[sandy666]

maybe it will help:

Power Pivot Limitations

 

[SOQLee]

UPDATE.

I had to create/insert a new worksheet and create the pivot table again to access the measure I needed.

When I worked from a copy of a worksheet with an existing pivot table linked to slicers (thinking I would just substitute measures); this is when measures were not appearing in the table fields.