Autopilot Approach mode inoperative

[sg_aviation]

Hi all,

today I noticed a strange behavior while flying ESNQ ILS Y Rwy 21. In the below screenshot I am fully established on both LOC and GS. However, upon selecting APP, the actually enrolled modes are ROL & VS (previous vertical mode). I tried re-cycling the autopilot without success. As a workaround I continued my approach using NAV & VS.

Does anyone have an idea what may cause this issue? I'm using the TDS GTNXi if that makes a difference.

Thanks,

Stefan