I've noticed something that worked in 10.5 is no longer working in 10.6.
We have a DWG seed file (version ACAD2013) and have been using it without issue in the past in ArcMap 10.5. However, this same seed file seems to be being ignored altogether by the Export To CAD Tool in ArcMap 10.6. By that I mean, the features exported are being symbolized with defaults (white line, continuous) and the layers that existed in the seed file template are not present in the output DWG file. The Export To CAD Tool is behaving exactly as if I had not selected a seed file at all. Has anyone else experienced this? I see that there are some known issues/BUGs with Blocks in ArcMap 10.6, but I haven't seen any mention of my issue specifically in the BUG report.
The closest I have found is Block Issue
same issue here