SmartThings | Scripts and tools for SmartThings

For this problem, I test it in my side and also reproduce your situation. It seems there is bug of liquid template in APIM. After reproduce your problem, I test in another APIM but it doesn't show same problem, the liquid template works fine in that APIM. Then I test in multiple APIM(with same set-body policy and request body) and summarize the result as below:

According to many test and the test result above, I guess it may be some bug after upgrade APIM. And the bug may be related to location or pricing tier(I'm not sure) because I can't find any differences between these APIM except location and pricing tier. So I suggest you to do same job in another APIM(with different location and pricing tier), it will solve the problem temporarily.

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I did some further test and found a workaround for this problem. I found the problem was caused by the line {% assign device_events = body.eventData.events | Where: "eventType", "DEVICE_EVENT" %}. If we don't assign body.eventData.events to device_events, instead use body.eventData.events directly in for loop like {% JSONArrayFor event in body.eventData.events %}. Then the liquid template works fine.

So we can just remove the line of "assign" and do "where" condition in for loop. Please refer to my liquid template below:

To build a block of bytes for transmitting, I recommend using the built-in ByteBuffer, which e.g. has helpers for 16-, 32-, and 64-bit integers in big- or little-endian.

You should then store the values as you use them, e.g.