so i have tried to input a amount of 100 diesel fuel to 300,000 lowgrade bot it only allows 10,000 lowgrade.

To help me better understand this issue, please answer the following questions.

1. Are you able to place 300k into the container?
2. If you can place 300k in the container, upon clicking Save and then Edit, is the amount still 300k?
3. If you are able to save 300k, does the amount on the shop UI display something different?
4. If the amount displayed on the shop UI does not match the amount saved, does the amount purchased match the amount displayed on the shop UI, or does it match the amount saved?
5. Which plugin are you using to configure stack sizes, and what have you configured for the max stack size of low grade?

1. I was not limited by how much low grade fuel I could place in the Edit container.
2. Upon saving more than 10k low grade and clicking Edit, the amount in the Edit container still showed the amount I placed.
3. The shop UI only showed 10k.
4. When clicking Buy, the amount spent was only 10k.

yes correct

Fixed in v2.2.0. Thanks for reporting!