Toot tips inside table form doesn’t always work

Hello,

Thank you for a wonderful plug-in, however I have n issue and hope to find an answer. I am using simple tool tips plugin to add some extra information to a time table. I uses TinyMCE to create a time schedule table. For majority cells it works well, but then on some whatever I do it doesn;t show up, even though I have exact same code in a previous cell. is there a limitation on how many tool tips can be put inside an element etc?

Would be very grateful for your advice.