Private Repos are not listed in Projects Combobox in Multibranch Config

Create a private repo in GitLab named "Test1" for User X. Create a GitLab access token for User X. Create a new multibranch Pipeline in Jenkins. Source is of type GitLab Project. Add the credentials for X:Access Token. Add the Owner (X) in the owner field. The form ponders the input and intead of -None- in the field nothing is displayed. Hit Save.

Log from the subsequent Scan:
```Cannot deserialize instance of `org.gitlab4j.api.models.Project` out of START_ARRAY token. ```

If a public repo is added in GitLab and the process is repeated, the public repo is listed in the Projects selection combobox, but still not the private repo.

Plugin Version: 1.5.1
GitLab CE Version: 13.3.6
Jenkins Version: 2.235.5