Mail rules that contain AppleScript pass the wrong message

When use AppleScript with Mail rules, Mail passes the wrong message to AppleScript.

If the AppleScript is in an Inbox rule, it runs on whatever email is highlighted in the inbox.

If the rule is triggered by a Mail Act-on keystroke, it run on an adjacent message to the one selected.

When triggered manually, the script works as expected, and on the selected message.

Same problem as here:

https://discussions.apple.com/thread/250106018

https://discussions.apple.com/thread/4820345

https://stackoverflow.com/questions/48304651/mail-apps-rules-are-sending-the-wrong-messages-to-applescript

Happens with all scripts, but this one is short enough to embed here:

global FlName

tell application "Mail"
   set theMsg to selection
   open selection
   set Dialogresult to the button returned of ("Process this email and Print as PDF" buttons
       {"Yes", "No"} default button "Yes")
   if Dialogresult is "Yes" then
...

Screenshots of rules: