VAT setup

can you give more information? product process example?

This is what an order looks like formed through the Order form https://prnt.sc/uqmsqr
This is how a document template is formed based on the Order https://prnt.sc/uqmu7v

Give an example, and what should be the VAT in this case, then eat how the system should calculate

VAT 20% must be calculated. When placing an Order, the following data is entered: Goods, quantity, price with VAT. And already in the order card: Sales price with and without VAT.

VAT 20% must be calculated. When placing an Order, the following data is entered: Goods, quantity, price with VAT. And already in the order card: Sales price with and without VAT.

You will give specific numbers based on the screenshot that you showed, taking into account the amount of 0.001

Order Card https://prnt.sc/ur4tp7
0.001 + 13500 (price with VAT)
In this scheme, there should be a VAT calculation of 20%
Order Account https://prnt.sc/ur504p

This is how it was configured earlier https://prnt.sc/ur57jp
Nothing is showing now

It is very similar to beans if everything was previously considered for you, try repeating the old order with the same amount and price as in the old order, if it counts in a new way and you have not changed anything, then this is clearly a bug
The system has VAT calculation settings, perhaps these settings have been lost or you have changed them
Also, in the template settings, you need to separately configure the VAT output, because it considers this is one thing in the order, and the output is another, there are own formulas
Your examples confuses the quantity, but it is very small and with a high probability rounding occurs somewhere as a result, the amount of VAT is reduced to zero
in general, give an example of an old order for example and make a new order if VAT does not converge, then yes, this is an obvious bug

Where are the VAT settings?

Write VAT in system settings

I tried to set the checkboxes here https://prnt.sc/ur7tij
But that didn't solve the problem

Then insist it's a bug
Just write specifics in style (I write anything, don't look for logic)
Here is the old order there, for example, 1000 * 1.2 = 444, and then 3333
In the new order, the numbers 1000 * 0.0001 = 333 should count, but counts 335
There is a mistake, please fix it
More specifics and numbers and examples
Based on my experience with VAT, I can tell you that this is a delicate thing and there are different organizations that think differently and accept reports from them because some refer to the code, others to "explanation"