Why does KMM think this category is closed?

[Jack]

I'm still struggling with the problem importing two dividend  
transactions into an investment account.  Even if I create the category  
(_Dividend) before the import, and test it by using it in a  
transaction, once I import, trying to edit the imported transactions  
fails, claiming it can't edit because the account is closed.  In the  
category view, the context menu includes new, edit, and delete  
category, and open ledger, but no open or close.  If I enable  
categories in the accounts view, it's the same options.  Is it even  
possible to close a category?  I'm assuming it is related to something  
in my kmy file, because if I import the same transacations into a new  
kmy file, they import fine, and I can edit them as appropriate.    
However, I have identified the key/value pair for mm-closed, and it is  
NOT present for _Dividend.  Why would the program claim it is closed  
when it is not, as far as I can tell?

Even stranger, if I import and then delete that category, whatever  
category to which I assign the transactions now claims to be closed.

In addition, once that happens, then closing the file (whether or not I  
save it) triggers the crash with "Unknown account id 'A000149' in file  
/home/jack/KDE/KMM/kmymoney-git/kmymoney/mymoney/storage/mymoneyseqaccessmgr.cpp  
line 206" in a popup, and

Qt has caught an exception thrown from an event handler. Throwing
exceptions from an event handler is not supported in Qt.
You must not let any exception whatsoever propagate through Qt code.
If that is not possible, in Qt 5 you must at least reimplement
QCoreApplication::notify() and catch all exceptions there.

terminate called after throwing an instance of 'MyMoneyException'
Aborted

on the command line.  Above this is

kf5.kio.widgets: No node found for item that was just removed:  
QUrl("file:///home/jack/home/finance/%23KMYDifference%23")
kf5.kio.core: Invalid URL: QUrl("KMM4.kmy")

but I'm not sure if those come from KMM or from some other program I  
opened from the command line.  A000149 is the investment account into  
which the transactions were imported.  I'm wondering if commit  
94b6b3235 (made by Łukasz 2017-12-25) might be responsible, since the  
account clearly does exist.  However, I also wonder if this error is  
really related to the closed category or not.

While I can continue to reconcile and update other accounts, I really  
don't want to reconcile this account for January without actually  
importing the transactions, so this is blocking keeping my file truly  
up to date.  I see nothing suspicious in any of the files or logs I've  
looked at - so I'm still open to suggestions on how to troubleshoot  
further.  (I suppose my next step is putting a breakpoint on this line,  
and then getting a backtrace to see where it's being called from - but  
again - this seems to be long after the actual problem occurs.

Jack