what error specifically are you getting? this is probably a different error or a different non-IUPAC character.
I checked this recently on the latest release of UNITE and it should work. (reposting from the tutorial since it looks like the code you quoted is not displaying correctly)
In 2019.7 some of the validators were updated, but I am not sure that's the issue — I just confirmed that this is working fine in 2019.7. Perhaps we have different versions of the database?
In any case, glad you are better now and got your data imported finally!