Problem with Thumsnap upload

[underwhelmist]

After writing a post and successfully uploading an image, I get the message box saying "close this message to return to your post", but there's no close button. I've been getting round it by using the browser's debugging tools to delete the popup and overlay elements but it's a pain. Anyone else seeing this? Chromium 67 on Debian 9.4 Linux.

[miniman]

Yes, it works for me if I just click elsewhere in the main browser.