Well. i also have a story about shields and shieldbugs...
Goes like this:
It was during a KvK my town was in the middle of the forest...
Last thing i did before i logged out was scouting a town, nothing there so i put on 2x 24h shields as allways.
The next day i had to go to my fathers house and help him building his new video editor PC so when i woke up i logged in to the game
checked the shield, there was 1d 6 hours left on shield so all was good, i logged out, did the trip to my farther and when i came home
6½ hours later and logged in to the game, i was zeroed.....
60m troops GONE, 8b silver GONE, about 13b of each other rss GONE and im pretty sure that my good mood was also GONE
all that was left was the smoke out of my ears!...
it was like the last 24h shield was'nt on even that it did say 1d and 6h when i checked it 6½ hours earlier....
i went to the support about it and all they said to me was that i had scouted a town, then i added 1 !!!! 24h shield...
So my guess is that sometimes as we all know, there is some "lag" in the game, and when you press that shield button in that same moment
the lag is there, it might show you that you added the shield, but it might not have been registered on the server cause of the lag,
so in my case, it only registered the first shield and not the seccond even that it showed me that there was 2d of shield applied...
so i allways! apply 2x 24h + an 8h when i log out of the game.... and set the timer in my head for only 34h of shield if one of them should have failed to register...