Q: What does the status 'Reviewers Invited' mean after 14 days in the 'Under Review' status?

I can thoroughly understand your confusion and anguish. However, it may help to know that this isn’t an entirely uncommon situation. This basically happens for either of two reasons. One, there may be a conflict of interest on the part of one or all reviewer(s). So, after picking up the paper, they must have realized this and then pulled back. Alternatively, they may have been assigned or even started the review, but may have needed to divert their attention to something more critical or with greater priority. So, they may have needed to opt out of this one. In either case, the associate editor (AE) now needs to look for one or more reviewer(s), and so, the status went back from ‘Under Review’ to ‘Reviewers Invited.’

As you can see, for now, you don’t need to think about “what’s wrong with your paper.” Your paper has been progressing in the system, except for this recent matter of reviewer challenges. You could wait for some time, say, a couple of weeks, to see if the status changes back to ‘Under Review.’ If not, that is, the journal is still finding it challenging to find a peer reviewer(s), and you know of any, you may drop in a mail to the editor with some suggestions.

Hope that helps.

You may also find it useful to go through these similar queries by other users.

• What does a status change from "Awaiting reviewer assignment" to "Reviewers Invited" mean?
• What does a status change from "Required reviews completed" back to "Under review" mean?

Additionally, you may also find it worthwhile to invest in this handbook: Keep calm and wait: A guide to understanding journal statuses

All the best for the next update!