For anonymization, we used another approach, also inside repeats:
The name field(s) have a relevant clause: ${SetAnonym} != "OK":
(based on acknowledge type SetAnonym variable, required, at the end).
An advantage might be that only on save the name fields are emptied. So an erroneous tick could still be corrected before.
But your trigger example needs further examination, e.g. by @LN or @Xiphware, please.
See also a similar problem reported in the past Incorrect (setvalue) trigger behavior in Enketo when used inside repeats - #6 by LN.