not really a bug I suspect, but…
in 9.0.4 the custom fields are not set, they must have been set in the last couple of earlier versions as I have never entered them in myself.
Also just a heads up, if you import a 3do object done with a earlier version of 3DC with customs fields set up differently, you will have to redo the fields for that imported 3do object if they are not the same.
I.e I imported a part that I had done ages ago, unsure which version now, anyway it had an extra field called FS10 ( i think it was) alone with railsim , railsimx etc. The railsim fields had entries Trainobject— etc
after import the entries in the part had moved alone in the fields, as an example Trainobject—- was now under the FS field.
bit confusin I know, but just a interesting observation.