have now tried it here direct - Virtual API / Variable 0 toggled by a DRB button & connected direct to the Light ...
doesn't work ... do need to go through the GL object ... with the output set to To True ... which maybe is a clue as to why ... though it may also be that Scenes don't toggle (as it were) ... and that Scenes set levels, not on or off ...
having the GL object might be advantageous, too, because can incorporate other interlocks, for more context-sensitivity ...
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btw ... just half an hour ago, I solved (thanks to an after-thought suggestion from my nephew) the POST problem ... the trick is to include - only for the Applescript / Shell situation (not Postman or Terminal, etc) a null data element ... ie: the problem was that the cURL was waiting on data that never arrived ...
ie: include -d'' (the '' being two single quotes) as follows :
do shell script "curl --location --request GET 'http://nnn.nn.nn.nn:nnn/api/v1/Objects/2213' --header 'Authorization: Basic nnnnnnnnnnnnnnn'"
do shell script "curl --location --request POST 'http://nnn.nn.nn.nn:nnn/api/v1/Objects/2213?6=1' -d'' --header 'Authorization: Basic nnnnnnnnnnnnnnn'"
simple, when you know !!