That's not really a problem with Prior's resolution. Rather, it's a different problem with self-reference, which appears whether we adopt Prior's resolution or not.

Compare: "P" and "P and P" are usually equivalent. But

"This sentence has five words." and "This sentence has five words and this sentence has five words."

don't have the same truth value. The problem seems to be that the meaning of "this sentence" isn't the same in the two ostensibly equivalent sentences. Whatever your favorite solution of this problem is, it seems that Prior could just graft that solution onto his own.

Prior's solution to the liar paradox needn't solve all paradoxes of self-references. As long as his solution is compatible with other solutions to other paradoxes, Prior has still contributed something of value.