After converting an Xbox One save to the "Bedrock" edition, I found that my beacons I had set up were not shining. After some testing, I found it's due to lava. They shine through everything else they're supposed to, and certainly used to shine through lava. I doubt this is supposed to be like that, since beacons shine through water.
Reopened - this was fixed in the 1.2.10.1 BETA, but the fix wasn't included in 1.2.10.2.