我可以使用MongoDB官方Golang驱动程序查找记录，但是记录为空

I'm trying to learn Go and I wrote a little code that handles a MongoDB test database, inserting some general "items". This is the code:

https://pastebin.com/ptNwKbk2

I can insert and update records without issues but when I try to FindOne or Find a record what comes out is some empty shell, it finds the record but the record only shows its id.
First Find [line 89]:

err = collection.FindOne(context.TODO(), filter).Decode(&resultItem)

Result:

Found a single document: {ID:ObjectID("5cb488c30eeb652e64ecdaeb") itemID: priority:0 desc:}

Second Find [line 95]:

cur, err := collection.Find(context.TODO(), emptyFilter, findOptions)

Result, every element has an id but no data inside ("itemID: priority:0 desc:"):

Found multiple documents (array of pointers): [0xc00004c840 0xc00004c8c0]

Could someone find what the problem is here?

Thanks in advance

The members of Items must start with an uppercase letter (just the variable names, the json/bson tags are fine) otherwise the deserializer can't access them.