Many thanks for the info, Geoff. For some reason, the license that was listed for our install of Events Calendar Pro was not the same as the license listed under my account. I updated the license, and the message went away – I am not sure if the old license was tied in with v3.x of E.C. Pro (which appeared to be installed but not active; I went ahead and removed it from our plugins), but everything appears to be working now.
As for the Filter Bar, it does not appear to be available on my download link, even though we have a license for it. I was under the impression that it expired the same time as our license of E.C. Pro, but that might not be the case.
Regards,
Doug