At the moment, there is an issue with Sim Update 5 of Microsoft Flight Simulator where altitude is read outside of the sim at a different value than what it should be (up to 2500ft away from where it should be) which may lead to issues with detection of the correct phases of flight in both PACX and smartCARS 2 and many users are reporting such issues.
Until a time that a fix is available, you may need to enter a different cruising altitude though the exact value is dependant on the weather in the simulator. A full discussion on the official Microsoft Flight Simulator Forums can be found here:
When a hotfix is released to patch this bug, we will edit this post or remove it. Until then, we can only apologise for the inconvenience caused by this change and remain hopeful that the MSFS team can resolve this issue as soon as possible. If you experience this issue, please do not open a support ticket as it is a known bug and our team will not be able to provide you any assistance on the error.