Yes My coworker and I both on MotoX had the exact same issue in Germany last week. Grayed out 4G symbol, swapping the SIM to another phone and that phone worked. Didn't matter which carrier in Germany we chose, O2, Vodaphone, T-Mobile, etc. they all behaved the same. No data roaming. Voice and Text worked fine.
Very annoying, spent several hours on the Phone with AT&T customer support with no resolution. Finally got them to provide me with unlock codes so I coul dpop in a prepaid local SIM to limp by.
FWIW, the AT&T MotoX did not have this issue on previous trips to the same location prior to the KitKat upgrade.
Since that time I have spoken to other co-workers with MotoX and we have one other than confirmed similar behavior for them Overseas.
The MotoX clearly has international roaming issues and should be avoided for international travelers until AT&T can resolve it.