When camel's IsSitting is 1, it cannot be set to 0

/summon Camel (some gr{NoAI:True}

Looking at that camel get it to sit. The command below is an example, use <tab> to make sure you're talking to the camel you want to:

/data modify entity 436e435a-8a3f-4e58-abad-1a2994fafbfa IsSitting set value 1b

The camel will immediately become sitting. Now try this:

/data modify entity 436e435a-8a3f-4e58-abad-1a2994fafbfa IsSitting set value 0b

The camel will remain sitting. Getting the value from shows no change:

/data get entity 436e435a-8a3f-4e58-abad-1a2994fafbfa IsSitting

shows "1b". It ought to show "0b" and the camel should have become standing.