When you invite him to join you, Imoen and Minsc will comment on your decision and during their comments the Continue Dialog button will be blank but still functional.Gate70 said:
The text on the "Continue" button should not be missing
1. Load attached BG:EE save.
2. Travel towards Nashkel Mine.
3. Speak to Senjak and Dorotea (1 > 1 > 1 > 1).
4. Kill Senjak, Dorotea and their bandits.
5. Speak to Dorn (1 x7).
Imoen dialogue has a blank Continue button.
Continue button should contain the word "Continue".