random build fails

hello.

I’m working on an interior archvis ue4 4.9.2 on mac (yosemite)

I have been working on it for a few weeks and I need to build regularly to see changes I have made.

My problem is that sometimes it builds, sometimes not.

Sometimes I have made no changes at all and it will build after a fail.

Im starting to get really superstitious and at one point I was sure that it was internet connection related but now seems not.

I have just had 7 fails in a row and its killing me!

Can someone please give me any information about this, any knowledge of what might be creating these random fails.

I also couldn’t find the logs, I looked through them all but I cant see which are the relevant ones.

Can someone please tell me where to find the exact logs I need and what i need to look out for.

Thanks in advance