There's a lot that can be going here but nothing that anyone can pinpoint a root cause without examining your system. For example, Formidable has multiple types of lookup fields, what kind are you using? How are you managing the lookup watch fields? "Because the number of entries seem to be too many for one of the fields from my Operator Table," how did you determine this was a problem? How many entries is too many? Please provide as many details as possible, include screen prints if it helps explain your process.

Hi Victor, Thanks for your feedback. I understand that Lookup fields can be tricky at times. To clarify, there was never a Formidable limitation for displaying the number of entries. The purpose to allow a "pre-selection" (Operators Category) was to reduce the number of entries the user would have to scroll through. Initially the Form worked fine. In the Aircraft Form I looked up the Operator filed from the Operators form. Once I added the Operators Category Field, I was no longer able to display any entries looked up from the Operators Table  -> Operator field. If I create a new "Operator new" Lookup field now in the same form to look up entries from the Operators form it never displays any entries. The Aircraft form has the field Operator Category (Lookup field - Image 01). I am looking up entries from the Operators form Operators Category (Checkboxes. Image 03). It is a "required" field and the number of values is limited to 1 (this field displays correctly). The next field in the Aircraft Form is the Operator field ( Lookup field, Image 02). I am using the Filter to filter by the field Operator Category.  and field Operators (Text, Image 04) (this field never displays any entries). When I add a new entry, I can select the Operator Category (Image 05). Like mentioned above, if I create a new Lookup field and try to lookup Operators directly without a Filter, I get the same effect with no list of entries displayed. First I assumed there was an issue with the checkboxes so I created a Text field and used the Text calculation to populate it with the value from the checkboxes. The outcome is the same in the Aircraft form. I can select from the Lookup of the Operator Category but I do not get any entries displayed for the Operator. I hope I do not need to re-create the entire form from scratch. I really appreciate you are trying to help me finding the problem.    

Here more screenshots

and the last 2

The problem was with the table where I am looking up the values from. There was never an issue with the cascading lookup. I found out when I looked at the setting and then the entries. When I clicked on the column heading of my Operator field, I would get a random order of the entries. While the sort with other columns was ok, the sort for 2 of the Text fields did not work. This indicated to me that Formidable had messed up my Form. I created a new form from scratch and imported the entries. Now all is good. It only worries me that I could have issues with forms in the future where Formidable messes up the form. Right now I do not trust this software and I am thinking if I should find another way to create my database. It is not the first form that I had to recreate from scratch.