2195141 - Error 311 when proxy tables being joined are pointing to different remote servers - SAP ASE

Running an UPDATE statement may raise Msg 311 when proxy tables being joined are pointing to different remote servers:

use testdb2
go
update tablea set flag=tableb.error_type from tablea inner join tableb on tablea.id=tableb.id
go
Msg 311, Level 16, State 2:
Server 'loopback', Line 1:
The optimizer could not find a unique index which it could use to scan table 'testdb1.dbo.tablea' for cursor 'C9'.
Command has been aborted.
(0 rows affected)
 
use testdb2
go
sp_helpobjectdef
go
 Owner Object      Type  Definition                        Usage    Status
 ----- ----------- ----- --------------------------------- -------- ------
 dbo   tablea      table loopback.testdb1.dbo.tablea       implicit NULL  
 dbo   tableb      table loopback1.testdb1.dbo.tableb      implicit NULL  
(return status = 0)

• SAP Adaptive Server Enterprise (ASE) 15.7
• SAP Adaptive Server Enterprise (ASE) 16.x

error 311, Msg 311, cursor, scan, unique index, proxy table , KBA , BC-SYB-ASE , Sybase ASE Database Platform (non Business Suite) , Problem