Hi Thomas,
I see you have shared the Slope Layer and WebMap with 'Open Data Collaboration Group' which is not required. You should only hared the content that you want to be in your open data site Publicly (Everyone) and with open Data designated group (MesoAmerican Research Center, I guess).
To troubleshoot issue, try refreshing indexes from Data tab of Open Data Admin site. If that doesn't work, try adding the tag/s again to the Item in question by editing them from Item details page.
I would suggest to log a support ticket if above doesn't work.
Cheers!
Hemant A