Piper Turbo Arrow III/IV Autopilot
Using Logitech Autopilot panel to control the autopilot function. Previously able to set altitude and vertical speed on Logitech panel and then engage AP. The AP will follow NAV and VS but previously when set altitude was reached it would automatically switch to altitude hold. Now it keeps climbing through set altitude on whatever VS is set and never holds altitude. The only way to achieve altitude hold is to set the VS to zero.