Some problems with tax and calculation rules

[GaryV]

Hi! We need in the section "Tax and calculation rules" to specify categories in which will apply discounts.
In General, everything is clear, but the problem is that we have a lot of categories and sub-categories, and the categories in which discounts will not apply only 2 or 3. If we choose all categories from the list and then exclude these two categories, in view of the fact that the list is still very large, it somehow is not saved (somewhere there is a limit to the number displayed?). Could you tell me how can I solve this problem?
Or there is other way. Specify the categories to which the discount will not be applied, but you need to change the code. What would you recommend?
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