Illagers stop patrolling when separated from their group and won't resume patrolling

Bug description

When an illager with the Patrolling:1b tag is separated from the rest of the patrol, the tag becomes 0b. This causes them to stop patrolling and wander around aimlessly, even having the PatrolTarget tag. The illager will not resume patrolling when it regroups with the rest of the patrolling members if the captain stopped patrolling himself.

NOTE: This bug doesn't happen in 1.14 to 1.14.4.

To reproduce

1. Summon a bunch of pillagers

/execute as @e[type=pillager] run data merge entity @s {Patrolling:1b}

/execute as @e[type=pillager] run data merge entity @s {PatrolTarget:{X:0,Y:64,Z:0}}

(or other coordinates)

1. Separate the pillagers
   → ❌ The pillagers lose their Patrolling:1b tag