We are presently testing Windows 10 Pro on a few systems as we determine what, if anything, won't work before we go ahead with a company wide upgrade.
I have the IT Manager who uses a Surface Pro 3 running Windows 10 Pro. He's got the full Standard 9.0.1.client installed, including Designer and Administrator.
When he first launches Lotus Notes and goes to his calendar, he only sees the colours assigned to the different types of entries, but no text
If he puts his mouse over one of the entries, it only gives him the time window for the entry.
The only way he can fix it temporarily is to go into the calendar preferences and change either the background or text colour (it doesn't matter which) and then change it back to the original settings and then save it.
It then says "rebuilding index" and he can see everything again.
This only works until the next restart of the Notes client.
I've installed FP4 because that's when full support for desktop versions was introduced, but that didn't make any difference.
I have Windows 10 Pro running on a desktop and another person has it running on a laptop. The desktop has the full standard client (admin, designer and client) installed and the laptop is just the Standard Notes client.
Neither of us are having any issues.