@conrefs disappear on DITA-OT --> PDF

I have a couple of appendices that use conrefs. These appear correctly when I open the doc in Frame, but some of them (not all, it is inconsistent) do not appear in the generated PDF file.

Is anyone else seeing this with recent versions? Is there a known issue, here?

I saw a similar thread thread here, but that was from 2010. It involved Frame 8 and tables. I am using Frame 2017 and the format is just <ul> items in body text.

Any advice will be appreciated.

–Randy Clark