I have flown this flight at least hundreds of times with the WT CJ4
and it always captured the Glide Slope.
Then it has stopped with the white GS on the bottom of the scoreboard.
You may be on to the problem.
I had always used “VS” to capture the altitude to 3,000 ft per ATC.
A few weeks ago, I started using “VS” to set it and then pressing “VNAV”.
Don’t remember why I decided to use VNAV.
I’m going to try it with “VS” only. I’ll reply if it does.
I’ve had that happen also. The WT CJ4 would fly down the
slope and at about, say less than 400 ft, I would turn off the “AP” and it would start to climb up and out. Straight out.
I think that I forgot to cut the throttle which was at 100% and maybe that was the reason. The “GS” was captured since it flew down the slope.