Incorrect counting of messages displayed in the contact list

[Valdnet]

Expected behaviour

Counting the correct amount of messages in the contact list.

Actual behaviour

The number of messages varies when the number is with and without the country prefix (+48). Counts only numbers without a prefix.

Server configuration

Nextcloud/ownCloud version: 18.0.1

Phone Sync 2.1.7

Client configuration

Android version: 6

Nextcloud SMS app version: 2.0.5