Meridian Flips under APT control


I've been using Astrophotography Tool through ASCOM quite successfully for controlling my OnStep systems, but just recently attempted to perform meridian flips using its automated sequence for the first time.  I've been unsuccessful in those operations.  Performing a meridian flip from either the SHC or automatically from limit settings works ok.  However, I want to use APT's process wherein when the target crosses the meridian, APT records an image, performs a plate solve, performs the flip and does another plate solve to reposition the telescope for subsequent image acquisition.   When I attempt it, I get the initial plate solve action, but then get an error message when the flip is supposed to take place.
Anyone know what I might be missing?  Or is this something that Onstep can't do with APT or similar programs (NINA, SharpCap, etc)?

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