I have also faced this similar issue and I got this resolved by implementing complex messages, like this:
Also you can include any custom html in any message also with this technique.
Implementing complex messages:
in modules di.xml:
Trigger complex message insteed of simple message:
create .phtml containing message content:
Just notice in the above of .phtml file having message content apply this:
I was able to resolve that sticky message issue by this. Please check if it works well for you.
More information on complex messages: