Recurring events: BYMONTHDAY is ignored

[heull001]

Checklist

• I can reproduce the bug with the latest version given here.
• I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
• I have taken the time to fill in all the required details. I understand that the bug report will be dismissed otherwise.
• This issue contains only one bug.
• I have read and understood the contribution guidelines.

Affected app version

1.2.0

Affected Android/Custom ROM version

GrapheneOS 2025021100

Affected device model

Pixel 8a

How did you install the app?

F-Droid / IzzyOnDroid

Which calendar service or provider do you use, if any?

Radicale

Which sync adapter app do you use for calendar synchronization, if any?

DAVx5

Steps to reproduce the bug

I have an event with following recurence rule:

RRULE:FREQ=MONTHLY;BYMONTHDAY=13;BYDAY=FR

Expected behavior

The event should recur only on every friday the 13th.

Actual behavior

The event recurs every month on a friday, for example 14. mar, 11. apr and 9. may.

Screenshots/Screen recordings

No response

Additional information

No response