When first activated, beacon beam flows downwards for a moment

^{I've done this many times before with bug reports like this}
Incomplete without a description for providing details.

Can confirm.

Cannot confirm for 1.8.4
What "Video settings..." are you using?

It occurs on all settings. It only happens for around 1/2 a second, so you have to watch closely to see it.

Still cannot confirm for Windows might be Mac specific?

I guess that's possible. Could another mac user confirm this please?

Do you still experience this bug in 16w15b?

Is this still an issue in the latest snapshot 16w44a? If so please update the affected versions.

This is an automated comment on any open or reopened issue with out-of-date affected versions.

Is this still an issue in the most recent versions (currently that is 1.12.2, or the latest 1.13 development snapshot 18w21a) of Minecraft?

Is this still an issue in Minecraft 1.13.1?