Encoding error with nested diagrams

Question

I can't encode a acitivity-diagram to svg format to occur the Ecoding error using PlantUML V1.2022.2. 

Without '-svg' option, the same activity-diagram was successfully encoded to png format.

And also, the same activity-diagram was successfully encoded on PlantUML Web Server.

PlantUML Web Server

@startuml

start

:aaaa;

:xxxx

{{

start

:bbbb;

stop

}}

;

:cccc;

stop

@enduml

The follwing bug has not been completely fixed.

Encoding error with nested diagrams - PlantUML Q&A