TEOZ mainframe overlaping box

Question

When using boxes and mainframe with teoz, boxes become hidden behind all diagram. That does not happen with puma.

Example:

@startuml Test
!pragma teoz true
mainframe **sd** Test

participant A


box
    participant B
    participant C
end box

activate A
A -> B ++:M1
B -> C ++:M2
C -> C ++--:A1
B <-- C --:R2
A <<-- B --:R1
@enduml

produces:

while without 'teoz':
 

@startuml Test
mainframe **sd** Test

participant A
box
    participant B
    participant C
end box

activate A
A -> B ++:M1
B -> C ++:M2
C -> C ++--:A1
B <-- C --:R2
A <<-- B --:R1
@enduml

correctly produces: 

Is there a way to fix or contour this behaviour?