So my issue is still not resolved:
I am no longer able to change the value of a global variable from within Netwatch.
If I create a script to change the global variable, and call that from Netwatch, the global variable will not change unless the policy option "policy" is checked for the script.
I verified this by a manual run of the script.
Since Netwatch can now only call scripts that have (at most) policies "read", "write", "test" and "reboot" - the script will not call when I check the "policy" option, as is seemingly required in order to modify a global variable.
Intuitively I would have figured that the "write" option would be enough to allow us to change a global variable. However it is the "policy" option that appears to allow us to do this. Not sure if it has always been this way, or if it is a bug.
Anyhow it appears that the usefulness of Netwatch is somewhat limited moving forward.
Following your method I got to have netwatch to execute the up and down scripts. As test I just wrote a line in the log and I checked both the run counter and the log. So fine.
Then I put some more lines in the same test scripts, and tried to run the command trying to execute a command, like /tool e-mail, it doesn't execute it and, moreover, doesn't execute nothing else before or after the command. This even happens just executing the script from Winbox or terminal.
So, probably the command execution inside the script itself is the problem, not only netwatch !
Is something you have seen in your tests?..