We inadvertantly added a BUG for imposition for 5.4.3. This may be the source of your impostion node changing behavior. To avoid this you could downgrade to 5.4.2 or wait for 5.4.4 which will be available in the very near future.
Seems to be getting closer. However, I noticed in the imposition preview, when its a single sided print the imposition preview is correct but when its a double sided print the imposition then changes. For exaple a single sided 5x7 with bleed will impose 4up on 12x18, but if its double sided it imposes 3 up.
In the imposition preset, verify the following:
One of the two settings may not have carried forward with the upgrade. If the above doesn't correct the issue and the incoming PDF page boxes are correctly defined, please escalate to the hotline.
It's always good practice to get a FreeFlow Exchange Export prior to upgrading. I've found importing the backup and selecting overwrite the confilcts has been a reliable way to fix something that may not have carried forward perfectly with the upgrade.
What SW version of FFCore are you using?
I have some workflows that have been set up and working correctly for a couple years now. They're set to put the maximum number up on the sheet. For example a 3.5x2in business card with no bleed would fit 30up on a 12x18. But now with the update they come through as 27up. Any ideas on why this would suddenly change? Is the a new check box or something somewhere I'm missing?