Inventory Widget: How to set the quantity to 1 only?

I am using the inventory widget and would like to only allow the selection of 1 from the drop-down.  When I set it to one, a number does not appear in the drop-down.

I was able to reproduce this from my end. I will create a report and pass this on to our L2 team for further investigation.

Thanks for the report. Let us know if you have any questions or if you need further assistance. 

I made another test and adding 0-1 value should add 1 value only. Please try that and see if that works for you.

Let me know if you have any questions.

Perfect, thank you!