FF23023: EVM return data invalid: FF22047: Insufficient bytes to read string value

I suspect there is a bug in the FireFly signer ABI encoding. This contract demonstrates the issue: https://mumbai.polygonscan.com/address/0xc0bc785b2c5494820B63c7108547b4652b9742aD#code

Steps to reproduce:

1. Create a new FireFly stack (using default settings with a local blockchain node is fine)
2. Create a contract interface / API with the contract listed above
3. Call the `POST` `/invoke/createCoupon` endpoint with the following payload:
```json
{
"input": {
"_end": "1234",
"_id": "2345",
"_ipfsUrl": "3456",
"_start": "4567"
}
}
```
4. Call the `POST` `/query/viewAllCreatedTokens` endpoint with an empty JSON object as the request body

Response:

```json
{
"error": "FF10111: Error from ethereum connector: FF23023: EVM return data invalid: FF22047: Insufficient bytes to read string value [tup,i:0,b:0][dyn,i:0,b:64][tup,i:1,b:128]"
}
```

On Polygonscan I see a valid response from this method should look like:

```
[[1,QmdbaSQbGU6Wo9i5LyWWVLuU8g6WrYpWh2K4Li4QuuE8Fr,1683555160,1683554160]]
```