The editor isnt working with the current version because it is out dated so you have two options:
1 - wait for the ME to be updated (wich can take a while)
2 - Use the 2.22 patch 1 of aces high, make your mission for that version and then just copy the RES of the mission to your 2.23 patch 2 version of aces high (since you will have 2 versions of aces high in diferent folders you will need to install manually the mission editor)