Unless you are in a great hurry, I might still suggest waiting until you get a response from Tech Support (perhaps @bw-admin can escalate your case?).
Export/import is not entirely lossless, so it would be better to fix the issue if one can be found on the back end. In addition, there is at least one other user who might benefit if the root cause if this issue can be found. If you do decide to pursue this with Tech Support, it would be a good idea to refer them to this thread.
What type of export did you create? You should choose a password-protected encrypted JSON for best results (not account-restricted JSON, and not CSV).