How do I use io_chunks to let xee auto-compute a chunk size relative to the request byte limit?

```
# By default, automatically optimize io_chunks.
self.chunks = self._auto_chunks(max_dtype, request_byte_limit)
if chunks == -1:
self.chunks = -1
elif chunks is not None and chunks != 'auto':
self.chunks = self._assign_index_chunks(chunks)
```
```
io_chunks (optional): Specifies the chunking strategy for loading data
from EE. By default, this automatically calculates optional chunks based
on the `request_byte_limit`.
```

The above is source code in `xee` that is supposed to automatically optimize `io_chunks` based on the request byte size (which is defined in the source code as approximately 48 MBs) when `chunks=None`. However, when I set `chunks=None` when running `xarray.open_dataset` I get back an xarray Dataset that is not chunked at all. What am I missing here?