jsg should I just let ASIAIR Plus handle everything?
Yes, but you do need to set the ASIAIR up to do what you want.
In the Mount Settings window, there is Meridian Flip menu that takes you to a window that lets you set two important parameters which control the choreography which ASIAIR uses to replace your own manual meridian flips.
The "Stop tracking x min before Meridian" is the parameter you mentioned. ASIAIR will stop exposures, then stop guiding, then stop tracking x minutes (in time) before the target coordinates reaches the Meridian.
After that, nothing should happen until...
... the time the parameter "Auto Flip x min after Meridian" is reached.
At that point in time, ASIAIR will issue a GOTO to the mount (yes; to the same coordinates as earlier). If the mount also thinks that the target has moved past the Meridian, it will then perform a Meridian Flip traversal. ASIAIR has no control of this path, it is done by the Mount. ASIAIR simply issues a GOTO. In truth, ASIAIR never executes an Auto Meridian Flip. What it does is to issue an Auto GOTO at the right time.
However (there is always a however), under this scheme, if the Mount does not think the target has yet transited past the Meridian, it will perform a "regular" GOTO, i.e., moving perhaps a tiny bit (since the mount has stopped tracking, remember). So, the mount still is on the original pier side.
This is why it is absolutely important that the Local Sidereal Time (LST) in the Mount and the LST in the ASIAIR is off by no more than that second "x" parameter in Mount Settings. And the longitude is off by no more than x * 15 arc minutes.
If the Mount does not actually perform a Meridian Flip, the ASIAIR will know by doing a plate solve. The plate solve determines if the camera angle has change, since a Meridian Flip will change the camera angle (why your images before and after a Meridian flip are inverted from one another).
If the ASIAR did not notice a flip, it will wait a minute and try issuing another GOTO. This keeps repeating until the Mount finally thinks that the object has transited the Meridian.
If you find that the mount takes many of these repeated GOTOs until it finally moves, compare your UTC time and your longitude on the mount with the same on the ASIAIR (the ASIAIR does not revel its LST because ZWO thinks that it is beyond the intellegence of the target audence of the ASIAIR). UTC Time and Longitude uniquely determines the LST at your location (i.e.the "Local" part of LST).
Now, it the UTC time and Longitude are correct, and the mount still has a delay in Meridian flipping, check the east-west leveling of the base of your mount (with a perfecty level base, the Hour Angle of the mount is equal to the LST minus the RA of target -- so an unleveled mount can also give you a problem with timing, unless your mount can model itself after more than 5 star syncs, and you have performed the syncs). Every 1º of East-West non-levelness can cause up to 4 minutes of time before the mount thinks the target has crossed the Meridian. Leveling your mount in daylight can save a lot of time later in the evening.
Chen
