This would explain your issue which is why I posted it.
Whatever PHP plugin you create has to conform to the rules of PHP.
You can not use single quotes for html inside a php string that is defined by single qoutes double quotes would need to be used.
If you use double qoutes in the line on the outside then your html can use single quotes inside. If you use double or single qoutes through out the string then you must escape any quotes you use.
Therefore if you do not want to escape anything your plugin would have to look like this
I go into this in depth in the tutorial I posted.
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