Hi,
I’ve been working on several typefaces since years using the /applicationsupport/adobe/fonts folder as target for testing fonts. This worked fine for me since a few weeks ago.
I’m doing a 2 masters / 5 instances font. When I export it to the “fonts” folder it causes Photoshop to crash (beach ball mode, then it makes all other apps start crashing on a chain). It might sound crazy but I reproduced same bug in 3 computers. If I install the font in the old fashion way (via fontbook or another font manager) it does work well but this is breaking my workflow and alerting me that something might be wrong with the file. I’ve tried all the tricks in my book but nothing hits the spot. Any idea?
I had similar problems with Photoshop. Removing all unneeded fonts from the folder solved it for me.
Hi Georg, thanks for your quick reply.
I have removed every item in the folder several times, then added selectively and it always happens again, the beach ball crash.
Just tried with almost all of this solutions and it looks everything has been back to normal. 
https://helpx.adobe.com/photoshop/kb/troubleshoot-fonts-photoshop.html