Newly added worker is not available for scheduling

I added a worker, then added him availability. He is displayed in the Workers list. But I cannot see him displayed in the Daily Planing calendar or in the drop-down list of Worker conducting the assessment (if applicable) during add/edit an appointment. Also, I can log in on his account and there he is unavailable for scheduling also.

checked on https://pdp-test.lcsb.uni.lu/