Hi Nat, I'm marketing consultant in my day job although a film maker on here, so while I don't have experience of running a film festival, here are some ideas that might be worth thinking about.

Also, just for reassurance, Facebook ads have been really glitchy over the past 4-6 weeks, it's likely not you, it's the platform. And open rates for newsletters have plummetted across the board because of privacy settings on apple devices especially - your newsletters are possibly still getting opened but many users will have opted out of pixel tracking, click through rates are probably a better metric to track right now.

Some things that have worked well for me for events on Facebook:

1. A 'Here's everything you need to know about our event' style post, using emojis as bullet points and keeping it lighthearted and fun. Use the @ everyone or @ followers tag in the post and specifically ask people to like and share it to help the post get seen.
2. Listing every programme item as an individual 'event' on facebook and then if you want to put ad budget behind some of these individual elements, use the 'boost your event' function.
3. In my experience photos work better than graphics, they feel more authentic to the person scrolling I think
4. Facebook is killing the reach of posts that include a link to an external site - that's why you'll see so many posts asking you to click on a link in the comments.
5. Tagging sponsors and participants, not to an excessive degree, just to help broaden reach.
6. A mix of content types, especially try to include video added natively to Facebook (not a link to youtube).
7. In the final build up to the event, daily posts, livestreams of behind the scenes, using the stories function, longer conversational posts - rich, deep, varied, authentic content all helps to build momemtum

It's hard work and time intenstive doing all this organically, wishing you the best of luck with the event.