issuances at vin > 0 rejected with "issuance transaction missing input"

I am getting the "issuance transaction missing input" when trying to register asset

So, liquidtestnet tx is [b31e7673…0b760f](https://blockstream.info/liquidtestnet/tx/b31e7673bef385dbe362ca5dce3d4b9da51efb27baef0560389f9b40a10b760f) (5 inputs, witnesses) with issuances at vin 1 ([7e3f5538…d1fa7b](https://blockstream.info/liquidtestnet/asset/7e3f5538427093443af02544da97589ce04d86f17e974cb8af1962d99dd1fa7b)) and vin 2 ([7a727315…097096](https://blockstream.info/liquidtestnet/asset/7a727315c4f64ba78fa25838d74d1546eb146a38135b64d9582d7e34c1097096)) (both commitment-valid, both rejected)

I am not sure whether it is related to this exact implementation

Got error during registration here: https://assets-testnet.blockstream.info

Can be reproduce with:
```
curl -sS -X POST https://assets-testnet.blockstream.info/ \
-H 'content-type: application/json' \
-d '{
"asset_id": "7a727315c4f64ba78fa25838d74d1546eb146a38135b64d9582d7e34c1097096",
"contract": {
"entity": {"domain": "lending.dev.blockstream.com"},
"issuer_pubkey": "0250929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0",
"name": "simplicity-lending/v1 lender-nft 33f1e0e7713359b97b1da992cdb83f6314b8ea3f32321b6f720c56340c56e472:6",
"precision": 0,
"ticker": "SLL33f1",
"version": 0
}
}'
```

Start by reproducing the failure with the provided curl request against https://assets-testnet.blockstream.info, using the linked Liquid testnet transaction and asset IDs. Trace the asset registration endpoint to determine why issuances at vin 1 and vin 2 are reported as missing inputs; done means both reproduced assets register successfully.

Written by the indexing model from the issue text.