I was on a bit of an extended break during my first reply, and didn't wish to break it once I saw you had figured out the problem on your own!
I can confirm that there is no technical issue - the whitelisted tags will only display recently added chapters that match all of the whitelisted tags. If no such chapters exist, then you wouldn't see any. I should've considered this immediately, but I'm glad you caught it on your own!
One thing that does still confuse me somewhat, is the fact that the white listed tags did not interfere with the "featured" or "random" chapters, nor recent images or even "most popular of the past 7 days." If this is intentional site design, alright, but it's honestly hard to tell.
I wouldn't say it's intentional, at least not in an "ideal" world, but due to technical limitations it's more or less how the feature has been implemented.
My apologies for the significantly delayed reply! Hope you worked out your tags in a suitable fashion in the end.