At the moment in my company does still exists some AEM 5.6 enviroments. One enviroment is used as a test system. The configured run mode of this is "publish.test.xxx". The problem with this one, it refuses to install bundles if those build as snapshot.
We've got an hint that we can change the log level for "autoinstaller" to TRACE so we can check what is going wrong.
Can some help me out what and how we have to configure it?
Do you see any messages in the log related to the OsgiInstaller thread? Are you not able to see the changes particularly for a class or nothing is getting change. Kindly download the jar and see if you are able to the changes there in a decompiler. Worth would be to deleting the bundle from crxde and deploy again. If it's only for a specific class adding immediate = true might help.
In addition, please check if the same bundle with different version also present. If you replace a bundle "mybundle-1.2.3.jar" with a newer bundle, but the same version number (in the Osgi metadata), this new bundle will never be started, but it will be ignored.
You have to increase the version number of the bundle to make it work. In a development mode you can also use SNAPSHOT versions; and for these the situation is different. Installing a fresh mybundle-1.2.3-SNAPSHOT.jar will replace an already existing mybundle-1.2.3-SNAPSHOT.jar
After installing the latest version of the bundle, Go to  and check if the bundle is still mapped to the older jar file.
If yes, there might be something wrong with the OSGI installer. You can follow the steps below:
- Stop the AEM instance
- Go to <AEM_Installation_Directory>crx-quickstart directory
- Rename the launchpad to launchpad_bkp
- Start the instance and this should create a new launchpad folder. Wait for the instance to startup
- Stop the instance and delete the newly created launchpad folder