Force application does not take effect immediately.
It took me 9 hours to force it
Horray DB2 Team!!!
From my own experience:
On the force of an application or the direct killing of the connected application the database must rollback uncommitted operations. If there's a large amount of work involved that rollback can take quite a bit of time. The application will still show until the rollback is complete. You can confirm with list applications show status - status of the force app will be rolling back.
Applications which are in lock wait status at the time of a force will not clear until they are able to rollback. The rollback is not possible until the lock contention has cleared. List apps will continue to show lock-wait until the lock contention clears and then the app will rollback any uncomitted work.
Were you trying to save the results of the query to a table? I have found that if there are several concurrent transactions a forced application can take a long time to disconnect since db2 is trying to write to as well as rollback through logs. If the logs are archived directly to tape then it has to get the logs from the tape system as well. Just my observation.