microsoft teams – Missed call tab

I'm breaking my brain with this one. We had the "calls" tab in everyone's Microsoft Teams client. Out of nowhere it seems to have disappeared.

We are currently in a hybrid configuration of SFB, we are not SFB online and we did not have the keyboard, which was fine, we were testing the functionality of the internal calls that worked very well! But out of the blue, the call tab has disappeared for everyone. We are still in the same version of Teams, so it is very strange.

No configuration changes were made as we know. I have activated a conditional access policy for Identity Protection and MFA recently, am not sure if that could cause that? These policies do not apply to trusted sites that all users have when they are in the office, so I am lost with it.

After seeing the equipment customer record, this is the result but I do not understand it

2018-11-27T21: 30: 32.346Z Inf UserAppsStore: Trying to add calls
with the following flags:
{"isCallingEnabledByTenant": true, "isSfbCloud": null, "isEvEnabled": true, "disableCallingForHybridVoice": true, "pstnType": boy / funny / boy / boy / boy / boy / boy / boy / human / evil / smoke / wood / smoke isCallingSupportedEnvironment ": true," enableVoipCallTab ": false," result ":" deleted "}
2018-11-27T21: 30: 32.346Z Inf UserAppsStore: Call application deleted,
flags:
{"isCallingEnabledByTenant": true, "isSfbCloud": null, "isEvEnabled": true, "disableCallingForHybridVoice": true, "pstnType": boy / funny / boy / boy / boy / boy / boy / boy / human / evil / smoke / wood / smoke isCallingSupportedEnvironment ": true," enableVoipCallTab ": false," result ":" deleted "}
2018-11-27T21: 30: 32.346Z Inf UserAppsStore: shouldShowCallingApp
resolved to false

Any help would be appreciated.

EDIT: You forgot to specify that the calls tab is also missing from the web application, not just the Teams Desktop Client.