Hello Pedros

Sorry, I can't get your issues clearly. Please explain in details. If possible, take a small screencast. Then share it through any drive.

Best regards

when creating an event in LMS, I cannot select any date, neither the date of event creation nor the start and end date, after clicking save, the dates are not saved. https://ibb.co/d4Gh6fq

Apology for the inconvenience. I have not found the issue on my localhost. Please share your administrator access here to check the issue. Use the Hidden Content box to share the credentials. Make sure that you have a full site backup before sharing.

ok

I have created a test event with dates. There are no issues.

I try edit, when i click save, data is crashed . Do you have some thing idea? Agein event "test" have no date.

Sorry, I did not find the issue. However, I would suggest you to upgrade your Joomla version to 4 or 5. Joomla 3 is out of support.