Tracker OS up to date - version 63.20001. 194.91 iPhone Fitbit app up to date version 4.18. When tapping on "install" in phone app a red line briefly appears and SpO2 does not install. All other tracker stats present and syncing as usual. N.B up to and including 31 May SpO2 was installed and working/tracking and syncing data fine to iphone app. Tried several tracker restarts and many iphone power off and on's. Anyone else experienced this and/or have solution suggestions please?