RealityXP GNS 750 and Carenado Cheyenne II Glideslope

I'm flying FSX SE with a Carenado Cheyenne II and RealityXP GNS 750. I'm having an intermittent issue with glideslope capture by the autopilot during ILS coupled approaches. I have tested the base GPS 530 that comes with the Cheyenne II and have not seen the issue. With the GNS 750, the A/C fails to turn off Alt Hold when reaching the glideslope. The autopilot annunciator shows GS Capture but Alt Hold remains on and A/C flies level. This happens on about 50% of approaches.

Any experience with this?

Thanks

marjimbo