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‘Period Problem is comma‘ has for some time been used as conjunction-adverb:
She had it all figured out to snare the throne for her son. Problem is, History had its own designs and agendas.
The debt ceiling was created to commit our nation to fiscal discipline. Problem is, fiscal discipline stands in the way of Life, Liberty and the pursuit of Happiness.
He made a perfect invention for a time-travel machine. Problem is, the machine can only be turned on in the past or future.
Long appearing even in formal texts, this usage is still somewhat ‘lurid‘ or ‘sensational,’ which seems to limit it to verbal uses or, if in texts, to creating a colorful or loose effect. No?