@rossini It is a good puzzle site
I can't think what the problem is. I just get a blank space where the puzzle should be. The problem has followed me through Windows 7 and Windows 10, several years of Opera iterations and across different laptops/desktops. I've always used standard installation settings (for both Windows or Opera). I don't know what to look at that might be the issue. I think that I'll just have to live with it.

@sgunhouse It is the original puzzles that have never played (all the Crosswords, Word Search, Trivia Quiz, Code Cracker, Sudoku). The newer puzzles play fine (Wheel Words, Crypto Quiz, Sudoku Shapeshifter, Addoku). I haven't come across any other sites where Flash content has caused a problem.

I've been using the Opera browser on Windows for years, but have never been able to use the browser to interact with any puzzles on the Lovatts puzzle site https://lovattspuzzles.com/online-puzzles-competitions/.
The puzzles work fine on Chrome, Microsft Edge, FireFox etc.
Is there an extension or setting I'm missing out on for Opera or is it a bug with the browser?