Dorico adding empty bars of strange length

I am having a very strange problem as I work on my score. I have reached the end of the passage written, and now I want to add bars to the end. I am writing a quartet, but what Dorico does is add bars for three instruments which are empty, and for one instrument there are rests. If I then try to write notes into the bars it seems to create bars of a different length (as if they are pickup bars or something?) Even when I add a new time signature the bar rests to not appear/disappear. I can’t really make progress with the score like this…thanks for any help possible! (See attached picture - the last four bars are the ones I’m trying to add…)

If you don’t think of the 4 bars you want to add, instead of the notes you want to add, Dorico will sort it out.
Make sure, you don’t have Insert Mode switched on…
Also try to forget about the new time signatures. Delete them, input the music, and at the end apply the time signature changes.

It may also be that the last visible notes/rests in what used to be the last bar have their “ends voice” property set. If you haven’t set this magically, or by using Edit > Remove Rests, it’s probably the result of leaving the Rest Visibility option ticked in Preferences > MusicXML Import (and then importing MusicXML). Either way, find and unset that property and the rests will return.