Buildcraft version: 7.99.7
Forge version: 13.20.1.2513 (1.11.2)

Link to crash report or log (on Pastebin or gist, please don't put the entire log here) :
Singleplayer/multiplayer: SinglePlayer 1.11.2

Additional information:

does this still heapen to you on 7.99.12?

closing as this seems to have been fixed and no responses

can you upload a forge log from when this heapens and also a debug crash report (hold F3 + C for about 10s ingame without having any gui's open)

Its going form the quarry into the chest, and then the from the chest into the storage

do you have any mods that change rendering (optifine and the like) installed?

No

Sometimes it starts flashing, and sometimes it comes back

In an hour prob

Hard to find but sure...

What happens specifically? Do items vanish for a short time in pipes before continuing? Do the items actually reach their destination (so are they inserted into the chest at the end?

They are in there, moving. They don't disappear- just they are not showing up in the pipes. They're still being transported, just are invisable. It got fixed when I reloaded the chunk btw

https://pastebin.com/7u7YUgXZ

I have updated back to 1.12.2 so I won't be able to show you the Debug crash report. Sorry! :( IF you really need it, I can pull it back up if you want me to.

I'm not sure how useful that would be... nothing is logged atm related to that...

Do you need any other investigation? I could go back to 1.11.2 and check the Debbuger crash report with the same settings. (I am not a mod expert but it would be logic that the Debugger crash report would have disappeared)