2391579 - Abort on "Destroying Locked Logical Buffer" from slib/s_bufman.cxx:5318 while operating on THG index -- SAP IQ

Server aborts on "Destroying Locked Logical Buffer" from slib/s_bufman.cxx:5318 while operating on a THG index.
sp_iqcheckdb() on THG index in verify mode does not show any corruption.

Function stack
-----
s_bufpartition::DestroyLogicalBuffer
s_blockmap::Destroy
s_blockmap::Destroy
hs_ohcMerge<s_btdiskblock, s_btitem, variable>::FinishMerge
hs_ohcMerge<s_btdiskblock, s_btitem, variable>::Execute
hs_ohc::DoProportionalMerge
hs_ohc::DoPushDown
hs_ohc::DoMerge
hs_subohcMergeUnit::Execute
dfo_THGMerge::FetchOpus
dfo_Scheduler::ExecWork
workAllocator::DoWork
hos_thread::Main
hos_lwtask::Start
-----

Additional logical buffer messages from iqmsg
----
           | I I N I I H I I I I I I I I I I H I H I |
Flags:  | s s e s s a s s n s s s s s s s a n e s |
           | D D e V B s B C W S P U M O S F s A a P |
           | i i d e u B l h a p r s a w t r A f d r |
           | r r s r s u o e s e e e p n a e f f O e |
           | t t D s y s c c h c f r   e l e f i f A |
           | i y e i   y k S A i e L   r e l i n T l |
           | a   a o   W M u r a t o       i l n x i |
           | b   l n   a a m e l c c       s i t n o |
s_buf(s)  | l   l e   i p V a F h k       t t y L c |
follow... | e   o d   t p a   L e e       P y A i a |
           |     c     e e l   B d d       a   r s t |
           |           r d i   u           g   e t e |
           |           s   d   f           e   a   d |
+----------+-----------------------------------------+------------+------------+------------+------------+------------+------------+-------------
| &s_buf   | A D N V Y W B C I S P U M O X F Z R H L | LockRefCnt | DBSpaceID  | BlkMapUID  | Blk Num    | _dskBlk    | BlockMap   | VersionRange
+----------+-----------------------------------------+------------+------------+------------+------------+------------+------------+-------------
0x7f1a88910ab0 | a D n V y w B c i s P U m x f z r h L |          1 |      16387 |     253446 |       2257 | 0x7f13e5f39000 | 0x7f1c5450f4e8 |   26682..26682
ERROR: Destroying Locked Logical Buffer
Buffer in main bufman

**************************************************
***   SAP IQ Abort:
***      From:  slib/s_bufman.cxx:5318
***      PID: 26726
***      Message: Destroying Locked Logical Buffer
***      Thread: 139748444509952  (TID: 956)
**************************************************

SAP IQ 16.0

Destroying Locked Logical Buffer; s_blockmap::Destroy; dfo_THGMerge;  s_bufman.cxx 5318, CR809505, CR#809505, 809505 , KBA , BC-SYB-IQ , Sybase IQ , Bug Filed