I’m sure there is an easy way to do this but I can’t find it.

4/4 time backing track with bass and drums, with final chords:
F F7 | Bb Bbm | F C7 | F |

This is for the final line of a song and I want to hold the Bbm chord (with no drum activity) for about half a second before continuing to the end.

Firstly, welcome to the forums.
There are probably two things to try.
1:
Follow the Bbm chord with an ellipses (three periods) followed by any instruments you wish to keep playing (e.g. Bass and Guitar, but not Drums)

2:
I think the only way to increase the time is to change the tempo on that bar. You can do this with the <F5> bar settings command, but it will work on the entire bar.

It's also possible to add an extra bar or bars between the Bbm and the next F chord. These bars can stay at the same tempo. I personally prefer this approach as it maintains the best tempo stretching possible. Sometimes slowing down a bar can create audio artifacts with tempo stretching. Since the "slow tempo" approach is the easiest, it's definitely worth trying first.

If adding a bar is required... To calculate how many beats in total you need, divide the tempo by 60 and then multiply the answer by 1.5 For example, let's say the song has a tempo of 80 bpm (beats per minute). This is 80÷60 = 1.333 beats per second. Therefore 1.5 seconds = 1.333 x 1.5 = 2 beats.

In other words, if the tempo of your song is 80 bpm and you add a bar between the Bbm and F that has 2 beats (using F5, bar settings), you will create a 1.5 second hold. Do not put chords in this bar and keep its tempo the same as the song's tempo. You will need to set the bar that contains F to 4 beats using bar settings (F5).

This works because the three dots/periods that Videotrack mentioned work across consecutive bars provided no chord is entered.

Thankyou for that.
The ellipsis is almost long enough but not quite, so I think I'll have to tweak the MIDI.
Which brings me to my second question.

Having performed a Factory Reset, when I "Save Special as MIDI" only the drum tracks seem to be transferred to the new file. I presume it's because the other channels haven't been assigned, and was a bit surprised to discover there apparently wasn't a default.

Again, I haven't been able to find how to rectify this & would welcome your assistance.

When you say that only the drum tracks are saved to a MIDI file, this is usually an indication that the style you are using contains Realtracks and not MIDI tracks.

Realtracks are audio tracks, not MIDI tracks which is why they do not save to MIDI files.

To check if your tracks are Realtracks, BIAB uses a color coding system. Realtracks have GREEN tracks names and MIDI tracks have YELLOW or PALE BLUE track names. These colours are in the mixer and across the top menu.

On the image below, Bass, Drums, Guitar, Strings are green. This means they are Realtracks.

The Piano is light blue so this is a MIDI Supertrack.

The Melody is yellow, so this is a MIDI track.

If this file were saved as a MIDI only the Piano, Melody and Drums will save. The reason the Drums save as MIDI even though they're a Realtrack is because all styles have an underlying MIDI drum track. This is not true of the other Realtracks, though.

Hope this helps.
Noel

Thanks for this.
Once I found out how to select an alternative MIDI instrument to replace the RealTracks one (not well documented) I'm now good to go.

JB

If you click on a RealTrack in the Mixer it cannot be changed to a regular (yellow) MIDI track. But it can be changed to a MIDI SuperTrack (blue). Click on "Select MIDI SuperTrack for this Track" in the menu.

If you want MIDI, you can certainly select a Custom MIDI Style to replace a RealTrack:

Great! Glad to hear you were able to get that sorted. Some people prefer to start with a MIDI style and then sub in RealTracks later, so that's always an option as well if you ever want to go that route. But of course, Realtracks still won't follow MIDI information so that is the downside there if you want to more closely dictate duration.