Hi @chennessy thanks for posting in the Lucid Community - I'm happy to help! The Markers options - seconds minutes hours days weeks months quarters years - are available to you depending on the length of your total timeline which is why you might see some options grayed out.

If your timeline has a longer duration you will be limited to larger delineations because it would be difficult to display many smaller intervals on that timeline. In my example above for instance it would be difficult to display a week divided into seconds minutes or hours. 

If you decrease your overall timeline these options will become available to you! I hope this helps - please let me know if you have additional questions. 

Thanks so much Micah - that's super helpful! I've changed it now and can see what you're saying.

Is it possible though to remove the date altogether and just have a time interval timeline? I need to do one for after 30mins of an event/incident then 1 hour intervals after that.

Thanks for your response! While it's unfortunately not possible to remove a start and end date from your timeline altogether an effective solution for you might be to hide the timeline labels entirely. This can be done by navigating to the bottom of the Timeline panel and toggling off the Show Labels option. 

This will allow the timeline and markers to remain without being associated with a specific date/time. Since you're wanting to represent 30 minutes after an event followed by hour intervals I would recommend combining multiple timeline shapes to represent the different increments. In my example below you can see my combination of two separate timelines the first with shorter intervals (in the panel set as "days") followed by another with longer intervals (in the panel set as "weeks"). 

Thank you so much Micah I really appreciate the clear and very quick help!

@chennessy I'm glad I could help! Please let me know if there's anything else I can do to support your work.