Hello Daniel,

Thank you for the provided details about this behavior and for commenting in this Bug Report item: https://feedback.telerik.com/blazor/1623568-appointments-are-vertically-misaligned-when-the-display-scale-is-not-100 

There has been a preliminary investigation of the bug and it coincides with your findings - the issue is reproducible even with the default browser zoom level. Additionally, it has concluded that the formulas for the appointment positioning calculations are correct. Also, the more the appointments - the larger the misalignment (and, especially to the appointments towards the bottom of the table). So far it appears that the borders of the grid below the appointments are causing the misalignment, but further investigation is needed. 

I've increased the priority of the bug and hopefully we would be able to fast-track a fix. 

I've related the current bug report to the older one linked above and I'm closing this one as duplicate. 

Regards,
Ivan Danchev
Progress Telerik