This seems to be a bug with the recent release of the Enketo which should be fixed with the next release of the Enketo. Will notify you when the same is fixed with the next release.
Kindly please be informed that the recent release of the KoBoToolbox which also includes the most recent version of Enketo (i.e. 2.6.0) should solve your issue.
For details, please feel free to go through the release announcement:
