word online file unlock bug (office online server 2016-05)

Hello.
I'm implementing a WOPI host.
It does not support COBALT (fsshttp, fsshttpb) so it sets "SupportsCobalt:false" for CheckFileInfo response.
Currently, it just responds 200 OK to every lock and unlock requests.
But while in tests, I found strange behavior of word online that seems to be a bug.
Belows are results of three tests. I opened pptx, xlsx, docx files in edit mode and closed office online webapp right after.

----- pptx

1. request lock
{
X-WOPI-Lock: {"F":4,"E":2,"L":"e4c2bba6790f408095b43bd8340e8826"}
X-WOPI-Override: LOCK
}

2. rename lock
{
X-WOPI-OldLock: {"F":4,"E":2,"L":"e4c2bba6790f408095b43bd8340e8826"}
X-WOPI-Lock: {"F":6,"E":2,"M":"e4c2bba6790f408095b43bd8340e8826","P":"2EE7D83D-84ED-48D6-8120-6C4D71FDF072","L":"e4c2bba6790f408095b43bd8340e8826"}
X-WOPI-Override: LOCK
}

3. on close, request unlock
{
X-WOPI-Lock: {"F":6,"E":2,"M":"e4c2bba6790f408095b43bd8340e8826","P":"2EE7D83D-84ED-48D6-8120-6C4D71FDF072","L":"e4c2bba6790f408095b43bd8340e8826"}
X-WOPI-Override: UNLOCK
}

------ xlsx

1. request lock
{
X-WOPI-Lock: {"F":4,"E":2,"C":"","L":"e4c2bba6790f408095b43bd8340e8826"}
X-WOPI-Override: LOCK
}

2. rename lock
{
X-WOPI-OldLock: {"F":4,"E":2,"C":"","L":"e4c2bba6790f408095b43bd8340e8826"}
X-WOPI-Lock: {"F":6,"E":2,"M":"e4c2bba6790f408095b43bd8340e8826","P":"35DCD4EF-F7F2-42FE-A758-3FFA27330695","L":"e4c2bba6790f408095b43bd8340e8826"}
X-WOPI-Override: LOCK
}

3. on close, request unlock
{
X-WOPI-Lock: {"F":6,"E":2,"M":"e4c2bba6790f408095b43bd8340e8826","P":"35DCD4EF-F7F2-42FE-A758-3FFA27330695","L":"e4c2bba6790f408095b43bd8340e8826"}
X-WOPI-Override: UNLOCK
}

---------- docx

1. request lock
{
X-WOPI-Lock: {"S":"da3613ea-b27b-42a6-adb4-4a6d89c4842e","F":4}
X-WOPI-Override: LOCK
}

2. rename lock
{
X-WOPI-OldLock: {"S":"da3613ea-b27b-42a6-adb4-4a6d89c4842e","F":4}
X-WOPI-Lock: {"S":"da3613ea-b27b-42a6-adb4-4a6d89c4842e","F":6,"E":2,"M":"e4c2bba6790f408095b43bd8340e8826","P":"BF334F9E-7899-4E39-9EA4-6EFF019F57DC"}
X-WOPI-Override: LOCK
}

3. on close, request unlock
{
X-WOPI-Lock: {"S":"da3613ea-b27b-42a6-adb4-4a6d89c4842e"}
X-WOPI-Override: UNLOCK
}

but there is no lock named {"S":"da3613ea-b27b-42a6-adb4-4a6d89c4842e"},
it shoud be {"S":"da3613ea-b27b-42a6-adb4-4a6d89c4842e","F":6,"E":2,"M":"e4c2bba6790f408095b43bd8340e8826","P":"BF334F9E-7899-4E39-9EA4-6EFF019F57DC"}.
because of this bug, when I use office online server with sharepoint 2013,
and set "SupportsCobalt:false" somehow,
word file modification is not adjusted because the file is forever locked.
(after about 30 minutes, the file is automatically unlocked,
but it seems sharepoint discards changes because of the transaction failure.)

I think this is an obvious bug and I want to know when I can get the fixed version of office online server.