There are many reasons for this, but I recently worked with a customer (you know who you are) that deployed 3-15 apps during OSD, some of the where Adobe CS apps and they are larger then Notepad++, just a bit. In this case the error was shown in the smsts.log file as “Install Dynamic application action failed to install application: ‘APPNAME’ Code 0x80004005” and Download Fail, hmm, running the same apps in a custom task sequence or directly to a collection works great of course.
Checking the cas.log shows that the Cache size is set to 5g (default) and going trough the log it turns out that after a few apps the cache is full and the cache cannot be cleared. Therefore the apps/packages cannot be installed, since files are missing.
(Note: There are are other settings that you should set in a Task Sequence as well, check out Peter Lofgrens blogpost https://syscenramblings.wordpress.com/2015/04/10/configuration-manager-custom-steps/)
That’s easy and not something new, just change the client cache size during OSD by making it a bit larger
Verify settings in the cas.log
In the cas.log you should now see.