Request for prefLabel return empty (not found)

[chinhnk]

Hi,

When trying out the REST API for classes I found that sometimes adding prefLabel to the include param causes the system to return empty (not found) results.
I have tried both GET and POST (batch request) and two examples are as follow

GET- with prefLabel

GET- without prefLabel

POST - with prefLabel

POST - without prefLabel

There are also some issues when I tried getting classes via general /classes method: sometimes some hundreds elements only contains @id and @type. Some other times, the collection field is simply empty - as follow

Could you please help me by seeing to these issues ?

Many thanks and best regards.
ChinhNK