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Yes, the problem was in my custom JS syntax definition, a long time ago I added highlighting for nested HTML in JavaScript template literals and apparently broke something…

1. Textastic builtin JS syntax

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2. My custom JS syntax

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JavaScript.zip

Hang for me, maybe it related with my custom CSS/JS syntax definitions. I'll let you know later.

Alexander have you tried opening syntax_test_html.html from my archive?

Unfortunatly Textastic not supported Subline Text syntax definitions V2

Yes its related with my custom html syntax highliting

The problem lies in "clear_scopes" settings