I do know that ACF uses an older version of select2 and for specific reasons, like there is functionality missing from the new version that is used by ACF. From my experience, 99.9% of the time the plugins that use the new version will work on the older version. The solution is usually to either prevent the other plugin from enqueuing its version of select2 or to dequeue/unregister it so that ACF can enqueue it’s version, but I don’t know the exact solution for any of the plugins that have this problem.
