ACL breaks Workbench

I'm using Workbench with Workbench Access and Workbench Moderation. When I enable the ACL module, I'm immediately asked to "rebuild permissions." As soon as I do, Workbench breaks and I can no longer view my drafts in Workbench by clicking "My Drafts." Disable ACL, and Workbench is fixed. Why does this happen if ACL is not supposed to do anything, but only provide ACL functionality to other modules? I added ACL as a requirement for Forum Access module, but I don't even have that installed yet. This problem happens after enabling ACL, before even adding Forum Access. Please help! We really need to be able to use both Workbench and Forum Access (which requires ACL). Thank you in advance for any assistance you can provide.