When I use optifine (testing with HD U G5) chisels and bits blocks are invisible. I have tried the instructions in #7 but that does not work. is there a known workaround for 1.12 to make the blocks visible? settings I can change on either optifine end or on chisels and bits end to allow them to work?

For any bug reports please provide the following details as well,

• MC Version: 1.12
• C&B Version: 14.33
• Do You have Optifine: yes.

if this should be working, I can provide more info, including a list of coremods which may be affecting the rendering engine.

Sadly 1.12 is not supported anymore, and as far as I know if the workaround in #7 does not work, then there is no way for you to get it to work.