Eddie,
For sure the WM control cycle for the component is still active. If you had set it up for your specific component or for a group of components for the same Production Supply Area (as it can be done for pick parts), delete the same thing first.
Because of your storage location reference/specific-setting in BOM or Material master, the storage location gets referenced in the production order's component overview. So again this storage location references the PSA, and because of the PSA the CC reference also gets in making it WM-relevant.
As long as the CC exists, system looks for the data from CC as a priority and considers it as a pick part and does a WM-level transfer.
So to solve the issue, please ensure that the reference to the PSA is not there in Work center or BOM or Material Master. Then everything becomes IM-relevant.
(My guess is you use a CC common for a specific PSA and hence this issue).
Check and revert back for further queries.