Non-waxed signs with clickEvents don't run the event when right-clicked

The Bug:

When right-clicking a non-waxed sign with clickEvent data, the sign is edited, instead of the clickEvent running.

Steps to Reproduce:

1. Place a command block and run the command provided below.

2. /setblock ~ ~1 ~ minecraft:oak_sign[rotation=8,waterlogged=false]{back_text:{color:"black",has_glowing_text:0b,messages:['{"text":""}','{"text":""}','{"text":""}','{"text":""}']},front_text:{color:"black",has_glowing_text:0b,messages:['{"clickEvent":{"action":"run_command","value":"say Hello"},"text":"TEST"}','{"text":""}','{"text":""}','{"text":""}']},is_waxed:0b}

1. Right-click the sign.

Expected Behavior:

Instead of the sign being edited, the clickEvent should run.