Hi Olivier,
We are sorry for the inconvenience caused.
We were able to reproduce the issue and have logged defect report regarding this. The fix for this issue will be included in our upcoming Service pack release which is scheduled in the end of May, 2015.
We have also prepared a workaround in which we have overriden the default style by using BasedOn property with the default key "DefaultSfBusyIndicatorStyle". Please find the workaround in the following link.
Workaround:
App1.zipPlease let us know if you have any questions.
Regards,
Bharadhi K