Basically what the title says, when rotating a blueprint with a boiler/heat exchanger it will keep its original orientation in the display. The ghost will still be placed properly so it's merely a visual error. Screenshots below show the original blueprint, how it's displayed after rotating, and how the rotated display comes out correctly after placement.
[0.17.0] Boilers/heat exchangers display incorrectly when rotating blueprints
Re: [0.17.0] Boilers/heat exchangers display incorrectly when rotating blueprints
Thank you for the report, it is Fixed for 0.17.1