Reference lookup list popup will use List v3 even when "Disable list v3" is checked.
Steps to Reproduce
1. Activate List v3 plugin
2. Open problem list view
3. Click on List Control in context menu
4. Check "Disable list v3" and save/update
5. Open new incident record form
6. In Related Records section click the reference lookup icon for the Problem field
7. Note that the problem list is still displayed using List v3 as a flyout modal screen right next to the reference field which cannot be moved, resized etc. instead of the expected popup window using list v2
Currently, there is no workaround. To receive notifications if and when more information is available, subscribe to this Known Error article by clicking the Subscribe button at the top right of the article.
Related Problem: PRB724412