Hi, Sharogen,
If you can take a screenshot of your combat log, and confirm that your character only made a
single attack roll, while the game took both your action and bonus action for two-weapon fighting, then that's definitely an issue. If you can take the time, please do consider submitting a formal bug report to Larian's bug form (Here:
https://larian.com/support/baldur-s-gate-3#modal), and include with your report your save file (including the thumbnail image file that will be in the same folder; they request both files), and a screenshot or screenshots that show the log and the issue; the more replicatable it is, the better.
