Hello, sorry this is probably due to an error on my part as this is my first deployment.
When testing locally, the multi select feature of my dropdowns were working fine. After deploying them to Heroku, they now only allow one selection.
It appears that callbacks are all working fine.
Here is the source code: https://github.com/chrs-ptr-hntr/AttainmentSuite/
And live link: https://attainmentsuite.herokuapp.com/
Update: Issue is also found locally. I believe it is a by product of callbacks updating other available dropdown options