AddWatcher Unimplemented in REST2 API

I face a problem using REST2 API to update RT Assets. I am using latest RT version (4.4.3).

I am able to read an asset successfully, using curl GET.
I am able to create an asset successfully, using curl POST.
I am also able, using curl PUT, to update any custom field or other field of an asset except: Status and Roles (Owner, Contact, HeldBy). They remain unchanged!!!

rt.log gives me at that point:
[error]: RT::Asset::AddWatcher Unimplemented in RT::Extension::REST2::Resource::Record::Writable. (/opt/rt4/local/plugins/RT-Extension-REST2/lib/RT/Extension/REST2/Resource/Record/ line 167) (/opt/rt4/local/plugins/RT-Extension-REST2/lib/RT/Extension/REST2/Middleware/

In addition, I discovered I cannot curl DELETE an asset!

rt.log gives me:
Failed to delete RT::Asset # 2431358 : Assets may not be deleted (/opt/rt4/local/plugins/RT-Extension-REST2/lib/RT/Extension/REST2/Resource/Record/

Regarding the DELETE action I found that I should update Asset status = ‘deleted’ and it worked! Also, previously referred inability to update asset Status works fine, I was wrong by mistake.
NOW, only Roles update DOES NOT WORK (RT::Asset::AddWatcher Unimplemented in RT::Extension::REST2::Resource::Record::Writable.)

Your assistance would be greatly appreciated!