Clicking on command sign runs all commands at once, regardless of which line was clicked

A sign generated with a command such as:

/give @p minecraft:oak_sign
{BlockEntityTag:{
 Text1:'{"text":"Right-click:","bold":true}',
 Text2:'{"text":"Floor B1","clickEvent":{"action":"run_command","value":"setblock -101 33 -293 minecraft:redstone_block"},"underlined":true,"color":"dark_blue"}',
 Text3:'{"text":"Floor B2","clickEvent":{"action":"run_command","value":"setblock -103 33 -293 minecraft:redstone_block"},"underlined":true,"color":"dark_blue"}',
 Text4:'{"text":"Floor B3","clickEvent":{"action":"run_command","value":"setblock -105 33 -293 minecraft:redstone_block"},"underlined":true,"color":"dark_blue"}'},
 display:{Name:'{"text":"Custom Sign"}'
}}

runs all the commands contained within the sign at once when clicked, regardless of which line the crosshair is over.