I turned dynamic chunk loading from 'multi-core' to 'normal', and that seemed to maybe have temporarily solved the problem. Today, I can't seem to reproduce the problem on demand, even when playing around w/ these graphical settings.
When I played MC last year or so ago, I recall having a similar issue (although at that time, it was not exclusive to one modpack, and this time it seems to be). Changing graphical settings temporarily fixed the problem then, but only for a few seconds at a time. I don't know what this means or what the likely culprit is. Maybe it's something wrong with my video card, drivers, or something else within my system?
Is it worth mentioning that changing natural textures or connected textures will restore the visibility of the crop sticks for about 3 seconds, before they disappear again? Changing one of those settings in any way does this, but only for a moment. I have no idea what this could mean, but it's very similar to what I experienced a year or two ago.
I'm running Windows 10, have 16GB of RAM, the default of which is dedicated to MC (4GB?), I am running fastcraft 1.24 & optifine 1.7.10 HD U D7, and I've got a gtx 980.
Are there any diagnostics I can give you to identify the problem easier? This just seems like it is too complicated and could be a million different things, I'm not sure how we could ever identify and fix the issue.
Here's what it looks like today...notice how it seems totally normal except for continuing not to display cropsticks: