How do you know that CM values are not being picked up? Is it falling back to default value from OSGI config? once you add/update the CM values it take some time to get it updated on the environment approx 15 min.

On your example file extension is missing from the url and if you think that url is correct then above response shows that the asset is no longer available on publisher

You can try accessing the asset file directly on publish url

Do you see any error on aem error log for the time of expiry?are you able to login on aem publisher and verify that asset is still present in Dam folder?are you logged in as administrator user on sandbox?

All the selector pages should flush automatically with publishing of main page. You might check the /statfileslevel and  /invalidatesection of your dispatcher configuration which works for doing the auto invalidation of the resource if certain node is activated/deactivated. check this blog.  https:/...

It seems issue might be located at this locationpathResource.getChild("datasource").getValueMap().get("tagsPath").toString(); You can check on code if any of the above is bill also please check the log correctly. Whenever there is an exception on the log trace it alleys show your java class line num...

Since, it’s not a prod environment, can you check the log level to debug mode and try to run the workflow for smtp mail trigger? This will give you more detailed information on the issue.Sometime it requires to whitelist your aem instance in address on smtp side fir this functionality to work. Can y...

Try updating the maven-scr-plugin version to the latest one 

Not possible via groups in aem

Its not recommended to remove those options at these OOTB functionality will help you in achieving other goals as name suggest in the drop down list but if you still wants to overwrite it you can do it by overriding /libs/dam/gui/content/assets/jcr:content/actions/secondary/create/items node inside ...