We have in the past had a related problem with importing, I can't remember the exact circumstances, but it was something to do with importing measurement data where there was some kind of ambiguity in the allowed values of the data. I don't think the problem was ever corrected, but we did find a workaround. The wizard was identifying errors which were not really there & highlighting them, but then when you rolled the cursor over the errors they would disappear, but the next button never became available even when they had all gone.

Basically there is some kind of failure in the process of recognising that there are no errors in the dataset to be imported so the bit of code which should un-grey the next button is never triggered. We found that if you edit one of the records (in the wizard) so that it triggers a genuine error, then re-edit the record so the error is no longer there, it then makes the next button available.

As to what you should edit to make this happen, that will depend on your dataset, but in our case it was measurement data in a field containing DAFOR values, I had set these up as a measurement in the term list so only D, A F, O & R were allowed (plus a few other codes). If one record was edited, putting an X in the field that would be enough to trigger the error. Best advice would be look to see if you are importing a field to which the term list has allowed values & try that.