The problem, which concerned signature key configuration, emerged late Tuesday evening. The apps had an issue downloading diagnosis keys from servers. Some of them displayed a loading screen notification that users weren’t able to dismiss by swiping away. Rebooting the device might get rid of it, but you shouldn’t clear storage in the app. That won’t resolve the issue and it may cause the loss of data and possible exposure matches.

The apps continued to collect keys (which are used for contact tracing) and to track potential exposures while the issue remained active. Google engineers will work with app developers to fix any lingering problems as soon as possible.

Google collaborated with Apple on a contact tracing system, which they released to public health agencies last May. However, it doesn’t seem that the issue has affected iOS exposure notification apps.

Update 1/13 2:45 ET: Updated to note that Google has issued a fix.