I just did a test and the trailing slash is not required (although it probably should be there).
Using PxPlus 2023 the following web page worked for me with or without the trailing separator.
<!DOCTYPE html>
<html>
<head>
<meta name="author" content="Mike King" />
</head>
<body>
[ttl]Cars[/ttl]<br>
<p>[form program=myprog]</p>
[list Cars$][data rowsep=/]Ford/Gm/Audi/Volvo/[/data][/list]
<br />
[list Cars2$][data rowsep=/]Ford/Gm/Audi/Volvo[/data][/list]
[/form]
</body>
</html>