Can't pick fields for calculation

Question

This is very frustrating.
I am editing the fields of an invoice form and want to use the last field of the line to create a total. I select the field and go into its properties. Under the "Calculate" tab, I select "Value is the 'product' of the following fields" and then click the "Pick" box to select which fields to calculate. I'm then provided with a list of all my fields and I tick my selections and click OK. But once I click OK, I am taken back to the Calculate tab with none of my selections in the fields box. Basically, it does not register my selections.
I have tried this every possible way I can imagine, restarted everything, etc. Still, no matter what I do I cannot get it to register the field selections I make for calculation. I managed to do this successfully for the first line in the form (seemingly at complete random) and haven't been able to reproduce any success for subsequent fields. I check the fields and once I hit OK it completely ignores them.
Any help here would be greatly appreciated.
RP

Answer 1

Consider using one of the other calculation options. For example, to use the simplified field notation option you'd enter something like this:
Text1 * Text2 * Text3 * Text4
This will work if your field names don't have any spaces or punctuation characters in them. It's possible to escape space and punctuation characters with the \ character, but it can get messy
The other option is JavaScript, which would look something like this:
// Set this field to the product of some fields
event.value = getField("Text 1").value * getField("Total1.1").value * getField("Another field name").value;
Note that you can include any field names you want inside the quote characters, so it's more flexible/cleaner than the previous option.