Users don't see some of the events, even though they participate in them

[akselnooit]

Impacted versions:
V13

Steps to reproduce:

1. Install Odoo and CRM module,
2. Create a Calendar Event. Leave show_as field empty or choose free option,
3. Invite another employee to your event as attendee,

Current behavior:
The other employee will not see this event in his calendar because of this Record Rule:
https://github.com/odoo/odoo/blob/13.0/addons/crm/security/crm_security.xml#L49

Expected behavior:
The other employee should see this event, as he also participates in it.

[pedrobaeza]

@tivisse are you the person to ping for this?

[Yenthe666]

Alternatively @tde-banana-odoo can be a helping hand here ;)