I can confirm the issue. This seems to be happening on firmware 2.1.0 as well, which is quite surprising because so far I can only think of one user who raised a question that’s related.
To summarize the issue: when the number of programs is a multiple of 3, the /jp command returns a string that’s incomplete (missing the ending ]} characters). I am pretty sure this has to do with the firmware sending out one packet per 3 programs. I am digging into it right away and will report soon. Thanks for reporting it and sorry about the trouble.