When things aren't working "as usual", I go back and double check on the usual. Good luck on figuring it out, one of my most recent issues ended up as needing an actual trip to the shop and a repair, the diagnostics just hadn't decided on that in the beginning.
Is there anything different about the fabric combination? Finer weave like batiks? Heavier??
You changed the needle but even fresh needles can have flaws. Have you tried different points? Mostly I use universal but sometimes a microtex sharp for those batiks or a topstitch needle for something a bit heavier than normal.
Lately I'm finding more and more problems related to bobbins, which can be anything from the bobbin itself, to the thread wind, to needing a case cleaning.