Since about 1.6 I have had this problem. I built the beacon block and built the pyramid out of gold and iron blocks. The effects of the beacon still work and it has the right range. Whenever I leave the area and return or even just walk into my base the Beacon freaks out and the large beam flutters and turns on and off. The only way I can fix it for a second is by pausing the game and returning to the game, but after a second the problem comes back. Please try and look into this.
MC-46616
Beacon block's beam flickers and glitches
Resolved
Fixed
0
Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases. If this has been done, we can reopen the issue.
Keep in mind that the "Resolved"-Status on this ticket just means "Answered", and that we are waiting for further information on whether this issue still exists or not. We will reopen it as soon as the requested information has been delivered.