I have no experience with the Elementor plugin or the Sydney theme… but I just installed the combo on a test site (no other plugin installed), and I couldn’t reproduce your problem: everything worked out of the box as seen in the screenshot below.
I’m wondering though, why are you using Elementor Dev
, the BETA version of the Elementor plugin, on a live site? Here’s what the plugin’s author says:
Important: Use with caution. Please do not use Developer Edition on production sites. Developer Edition releases, just like beta releases, may not be stable. Use it on staging environments only, and back up your entire website before updating.
I’ll recommend you get rid of the Developer Edition (aka BETA version)… unless it has a feature your site depends on what is not available in the standard version.
And if after switching to the standard version you still have this problem, you may wasn’t to post in the respective addon’s own support forum, so their developers can look further into this for you:
Elementor Support Forum: https://www.ads-software.com/support/plugin/elementor/
Sydney Support Forum: https://www.ads-software.com/support/theme/sydney/
Good luck!