SWF_RUN 611 Execution Interupted

[Mark Pyc]

G'day Wuggers,

It's been a long time! Hope you're all well.

I have a situation in an ECC6 / 7.00 system where an IDOC error
handling WF is sporadically failing in a very odd way.

The WF History shows error SWF_RUN 611 Execution Interupted at the Flow level.
The first step is listed with a Workitem ID / Step Number / Creation
timestamp but no other info (No WI Text, No Created By)
That first step Workitem ID does not really exist! It's not in
SWWUSERWI. It can't be displayed with SWI1.

Normally when I see "Execution Interupted" I expect to see an ST22
short dump or something in SM21 System Log, but there is nothing.

It seems very odd that the WF Log is written to with a Workitem ID,
but there is no other trace of it in the system, and no logged
failures that I can find.

This first step is a Dialog task based on IDOCAPPL.INPUTFOREGROUND and
uses a copy of standard Rule 30000013 (copy has "Terminate if no
Result" selected).

If I use SWUE and raise the same event for the same instance the
Workflow processes correcty. This suggests to me that there may be a
timing issue where the WF is triggering before the IDOC is fully saved
to DB, but even if this is the case it doesn't explain why there isn't
any proper error capture and why the WF is left "In Process" with a
child WI logged but not actually created.

I can't find any OSS notes / WUG or SDN Posts that really help.

I and the 3 other WF consultants here are baffled. Any ideas?

Have fun,
Mark