Are you using the Repeats ending function? If so you should first turn off the BIAB repeats by changing number of choruses to 1 and setting the number of bars to say 200 (we can fix the number later.

Then build your song in a linear fashion. Bar 1 to the end including any repeats and DS or DC functions. If you do this you won't need to insert or generate bars. When you play it, it should sound the way you expect.

Now you should be able to put the DC in place correctly.

You need to take a look at the repeat list. It's in the repeat dialog at the bottom. Click the 'Edit List' and you can see the formulae for your endings etc. They need to be in the right order. You can reorder them if they're wrong.

I just think of them as print functions. the functions never change anything in your music - they just make fake sheets.

It's not intuitive, but I have hundreds of pieces of music with endings, repeats and ds and dc.

BIAB for Windows Version 2019 (643)
Windows 10 (1909)