Strange featureGroup behavior with svg icons (they are not displayed)

Description

I added icons for markers as svg-code. Inside featureGroup icons aren't displayed on the map (while markers themselves are presented and svg-code is in the marker too). In the same time, in devtools I found strange div block inside the map with display:none styles with all my icons inside again. If I remove display:none, I can see all my icons.

Live Demo

https://codesandbox.io/s/suspicious-spence-tu812 (components -> HelloWorld.vue)

Steps to Reproduce

See the demo (map in the sandbox isn't working well but the icons behavior is the same as on my localhost)

Expected Results

I see marker's svg-icons inside featuregroup

Actual Results

Icons are not visible

Browsers Affected

• Chrome
• Firefox
• Edge
• Safari 9
• Safari 8
• IE 11

Versions

latest