Unless the checkbox shown in the attached pix is checked, no skin will show the tab close "x".
This is a fairly new change to JRiver in the last year - I know, because I'm the one who requested the change. The close button makes tabs much wider and is unattractive IMO. I requested the ability to close tabs via middle click (just like Internet browsers do) and give users the option to hide/show the close button in order to reduce the tab width if desired. It was well received by those who participated on that particular thread and is now a part of JRiver.
Bottom line, reinstalling MC will not help. Only one skin does not show tab close "x" regardless of that checkbox setting, and that is the current
Dream In Blue. I know this because I'm the
Dream In Blue skin author. I hated the close tab button so much I purposely left it out of my skin XML file altogether. That said, if you really want to add it back, I described how to do it in the initial post when I launched that skin:
https://yabb.jriver.com/interact/index.php/topic,128460.msg891359.html#msg891359If you follow the instructions contained in that thread, you will then be able to hide/show the tab close button like you can with every other skin.
I've have had a
Dream in Blue update in the works for the last year, and I keep promising I am going to release it any day, but I just keep finding ways to procrastinate completing the final touches. But when I do, the tab close buttons will be there by default so that the tab close hide/show setting will work,
without any XML file customizations required by the user.
I hope this lengthy answer completely resolves the OP's issue.