Hello C.
A possible workaround is to add tabulation ('\t') on the different conditions, as:
@startuml
start
while (\t\t\tendless loop\t\t\t)
if (\t\tcondition met?\t\t)
:activity 1;
while (while condition)
:activity 2;
endwhile
endif
endwhile
end
@enduml
[See on PlantUML online server]
If that can help,
Regards,
Th.