It looks like the MCZ members are indeed enjoying their vacation.

With no new updates from the members yesterday, fans began to speculate that the group was taking a long break. Just then, SHIORI updated her Instagram. Along with her New Year's greetings, she confirmed that - as expected - she is currently on vacation.

Here is a summary of her post:

I haven't shared my New Year's greetings yet. 
Happy New Year, everyone.
 I hope to stay healthy and have fun again this year. 
Thank you for your continued support. Sorry, but I am still fully enjoying my time off!

Meanwhile, AYAKA mentioned on a recent episode of her Podcast that she was traveling to a "place that wouldn't surprise anyone," suggesting that she, too, is enjoying a getaway somewhere.