Windows 10 is buggy. Do an Internet search for "Is Windows 10 Buggy" or other terminology. I found this post:
This page and many others indicate that once again Microsoft has released a beta version of an operating system and that users are unhappy.
FileMaker 14 offered many new features and it was also a beta version released to users who are unpaid beta testers. The script editor was unstable in Windows 8 with script names disappering but reappearing later when the file was reopened or dropping to the bottom of the list on a regular basis. The script editor also had buggy features and even now in v4 some problems exist with saving a line and inserting a new line using the enter key. But that's the price with using new software. Apple also serves up its usual feast of bugs when creating its latest OS update or upgrade.
My standard for software updates has been for over 25 years to not upgade to a new version until it was at v4 and the cries and gnashing of teeth of early adopters had died down. I often broke this standard and paid the price.
Naive users have often installed the newest update and suffered the fate of the early adopters plus the unexpected changes inside the new version. One remarkable problem occurred after Y2K when any software company that did not require 4 digit years found its users with big problems with dates.
Many FileMaker users are first time database creators and unaware of the problems they face even in a stable environment. A first time user can only buy the latest version whether or not it is stable and bug free. This applies to the operating system on a new computer or tablet or phone (with exceptions of course). There's little this buyer can do other than be patient and wait for the oncoming updates. I've suffered through a great many of these situations and now how frustrating and painful these problems can be.
Business Rule One: never upgrade a working FileMaker solution or the networks operating system until you have thoroughly tested it. Work on a secondary copy of the main file on a development machine and test, test test. When you are satisfied that it it bug free, within reason, then you can update your current files. There are rules about this and others can discuss them with you.
I have avoided installing Windows 10 for 3 reasons:
1) I don't need the headaches of being a beta tester.
2) My current Windows 8 is fairly stable and works well, so why upgrade.
3) Windows 10 is probably selling my data to its buyers and scraping my drive for every bit of data as does all 'free' software.