cannot make wolf angry using commands

I cannot set a wolf to be angry using commands. I have tried this two ways, using a function and with typed commands.

To reproduce, summon a wolf, probably inside a pen so it can’t run away.

Create a function with the contents:

execute as @e[type=wolf] run data modify entity @s angry_at set from entity @p UUID
execute as @e[type=wolf] run data modify entity @s anger_end_time set value 1000000

Then invoke the function. The wolf does not become angry (it doesn’t change to the angry texture, nor (afaict) act in an angry way.

I have tried typing these from the command line and had the same (lack of) result.

Speculation about the problem (I’m probably wrong): I’m thinking this is because neither angry_at nor anger_and_time are valid without the other, so when I set (say) angry_at, the system notes that the end time does not have a positive value and so ignores the command. I obviously could be wrong about this.