Testing #91095:

• use vscode-mock-debug project
• change the code in mockDebug.ts:85 to

    		if (text === 'start' || text === 'startCollapsed') {
    			e.body.group = text;
    			e.body.output = `group-${text}\n`;
    		}
    		if (text === 'end') {
    			e.body.group = text;
    			e.body.output = ``;
    		}

• use a readme.md file with this content:

  log(start)
  log(arbitrary line of text)
  log(start)
  log(arbitrary line of text level 2)
  log(another line of text level 2)
  log(end)
  log(another line of text)
  log(end)
  

• run the mock session with F5
• step through the test input line by line

Observe:
grouped output works fine:

• stop debug session
• set a breakpoint after the log statements
• start debug session and continue (in one go) to the breakpoint

Observe:
grouped output no longer works:

The group nodes are empty and all log statements are listed flat.