Using the 1.8 VM I ingested two PDFs with a DOI that has been previously known by Altmetric - http://dx.doi.org/10.13140/RG.2.1.3302.5680. A badge for another version of this item displays elsewhere - https://uwspace.uwaterloo.ca/handle/10012/10323.
I entered the DOI into the Location (URL) field of the PDF content model.
It failed with the default DOI XPath setting.
I also edited the configuration to /mods:mods/mods:location/mods:url[@type="doi"] which also failed.
I confirmed that the Altmetric block was enabled.