Can't Read Seeds from Envelope-CLI into GST

I created a few seed envelopes with envelope-cli:
```
SEED=$(envelope generate seed)
SEED_E=$(envelope subject type ur $SEED)

ur:envelope/tpsotantjzoyadgdtburldbkjpjeclprcnwpfnsrcakkgdwmprkgvlzc
```

And then with some metadata:

```
SEED_E=$(envelope assertion add pred-obj known note string "Zcash seed" $SEED_E)

ur:envelope/lftpsotantjzoyadgdatiniegmvsstbnahfxglenaasrbycmvdoyaatpsoimhtiahsjkiscxjkihihieaypkwepr
```

Reading either into GST results in "Envelope does not contain a seed."

(Obviously, the envelopes will vary based on the seed generated in step 1, but those commands should generate similar seeds, which I assume will similarly not read in.)