Here is the test video:
Crops will despawn if their growing requirements are not met.
This can happen when it's too dark, when the crop hasn't been watered(this is separate from farmland turning into wet farmland) and similar.
It especially happens with high-stat crops, they are hard to keep growing sometimes.
What are your circumstances?
I know, but ... this problem is different.
The plant disappears just a few seconds after planting, and if the same seed is planted after that, the new plant could grow normally.
I think it is a bug of new IC2 version because it havn't happened on MC 1.10.2 and previous versions, but in 1.12.2, it has about 20% probability.
You can refer to this video:
Hello dear IC developer,
I am a MC player from China, now I found a bug of IC2 2.8.187, sometimes corp will disappear after planting for a moment(a few second), this issue occurs almost every time after a large-area plant.
I record a video of test, if developer need, I could send it by e-mail.