Sudden appearance of fractional coordinates

Using Builds 0947 through 1092 with a UPM OF 2000, several years past I produced a finely-detailed connecting script. Now, using the latest Build 1270, when I open the Glyphs file to do some additions I suddenly have a very large number of fractional coordinates appearing. I have never used those at all, always making sure nodes are on the grid. My grid setting is 1/1.

What has caused this change? I can foresee a lot of work for me to fix it because when I do Cmd-A and shift the outline 1 unit and back it sometimes causes additional problems. I know how to fix everything but it is just a lot of additional work.

Path > Round Coordinates should be better than moving the nodes.