Currently, JQL queries involving fields of type "Select List (multiple choices)" don't support operations such as calculations or number-based comparisons. This limitation affects users who need to perform searches that involve numerical evaluation or arithmetic logic on these fields. Since Select List fields often contain numerical values or data that can be quantitatively assessed, extending JQL's capabilities to incorporate these operations would significantly enhance its utility and flexibility.

Workaround: Using a Custom Number Field for Numeric Operations on Select List Fields

While JQL can't perform calculations or number-based operations directly on the "Select List (multiple choices)" fields, a workaround can be implemented to achieve similar functionality. Here is a step-by-step guide to setting up this workaround:

• Create a Custom Number Field: Set up a dedicated number custom field, such as "multiple-select list count," in your Jira instance. This field will be used to store the count of selected options from the Select List field.

• Automate Field Updates with Automation for Jira (A4J): Use Jira's Automation for Jira (A4J) to automatically update the "multiple-select list count" field whenever an issue is created or updated.
  In the automation rule, use the smart value issue.customfield_10239.size() to count the number of options selected in the Select List field (replace customfield_10239 with the actual custom field ID of your Select List field).

Once the "multiple-select list count" field is populated with the count of selected options, you can perform numeric queries using JQL. For example, your JQL query could be multiple-select list count > 1 to find issues where multiple options are selected.