Sorry you have to deal with this, this sound horrendously annoying especially if you have over 100 products. However, this most certainly sounds like a bug within your app as it should not normally be like this.
To double check, I tried to recreate the situation. I imported a ring from the Oberlo marketplace with different colours. I deleted the description in the import list. Then, I split it into four different variants. Afterwards, all the descriptions stayed deleted. I made you a brief video showing the four different variants with their deleted descriptions.
Could you please email our support team at email@example.com? They will be able to log in and escalate your bug to our developers so they can see what is going on. Hope that helps, sorry again about all that trouble!