We (LM Studio) found the bug with the 31B model and a fix will be going out hopefully tonight
My guess is that they found a bug with their implementation of the model using the weights Google released. These bugs are often difficult to track down because the only indication is that the model is worse with your implementation than with someone else's.
This particular instance was a fix to the output parsing [1] in LM Studio, described like this:
"Adds value type parsers that use <|\"|> as string delimiters instead of JSON's double quotes, and disables json-to-schema conversion for these types."
[1]: https://github.com/ggml-org/llama.cpp/pull/21326/commits/a50...
edit: formatting