No streams can be found

When I try to either list streams or get all/a specific one, nothing seems to be found.

```
$ awslogs streams --aws-region us-east-1 /ecs/libretro-superbuild14-s3
$
$ awslogs get --aws-region us-east-1 /ecs/libretro-superbuild14-s3 ALL
$
```

However, using a start time does seem to work:
```
$ awslogs get --aws-region us-east-1 /ecs/libretro-superbuild14-s3 ALL -s1d
/ecs/libretro-superbuild14-s3 ecs/libretro-superbuild14-s3/2100c359-0829-4786-a78d-1838dcc1f822 PRETTY_NAME="Ubuntu 14.04.6 LTS"
/ecs/libretro-superbuild14-s3 ecs/libretro-superbuild14-s3/2100c359-0829-4786-a78d-1838dcc1f822 VERSION_ID="14.04"
/ecs/libretro-superbuild14-s3 ecs/libretro-superbuild14-s3/2100c359-0829-4786-a78d-1838dcc1f822 HOME_URL="http://www.ubuntu.com/"
...
```

And listing groups (not streams) works fine. I'm using 0.11.0 from pip on Arch Linux.

Any idea what might be wrong?

Reproduce the awslogs streams and get commands with and without the -s1d start-time option, comparing them with the working group listing. Trace the CLI paths for stream discovery and time-bounded retrieval, then verify that listing streams and retrieving ALL work without an explicit start time.

Written by the indexing model from the issue text.