Why doesn't snippet work inside a block?

Question

Pug

In general, the essence of the issue.
Used by pug + bemto
There is the following snippet:

<snippet>
    <content><![CDATA[
= '\n'
// begin $1
+b.$1
    $0
// end $1
= '\n'
]]></content>
    <!-- Optional: Set a tabTrigger to define how to trigger the snippet -->
    <tabTrigger>bl</tabTrigger>
    <!-- Optional: Set a scope to limit where the snippet will trigger -->
    <!-- <scope>source.pug</scope> -->
</snippet>

when calling bl->tab , we get the following:

= '\n'
// begin 
+b.
    
// end 
= '\n'

And when I hit the $0 point with a tab when I call snippet'a bl->tab again , nothing happens. It probably has something to do with the bemto plugin itself.
Does anyone have any ideas how to solve this issue?
thanks in advance.