Show without tax in admin makes incorrect invoice fields in orders

[gernot]

https://www.proteawines.jp
ZC 1.5.6c, MariaDB 10.2.x, some Japanese language customizations, Edit Orders, etc.
Will update later if needed, away from system.

We noticed that in the invoices seen in Admin, the fields for prices without sales tax and those with sales tax are identical (both without sales tax), but the grand total for an order is fortunately correct (i.e., includes tax).

It turns out I had in Admin Settings "show prices with tax in Shop" and "show prices with tax in Admin" both set to "false" as intended, since I want to see the net prices when I look at items.
When I set the "show prices with tax in Admin" to "true", then the with sales tax fields in the invoices are correct (and the ones without tax stay as they were).
Now however the prices of items are shown with tax in other parts of the Admin, which is something I want to avoid.

Both I and my partner completely missed this for a year at least, so I am not sure if it is intended behaviour, a bug, or a result of me installing an add-on (like Edit Orders for example).

[lat9]

I'll just mention that Edit Orders requires that both of the "Show prices with tax" settings to be the same.

[gernot]

Hi lat9,
Hmm, that is interesting, I will read up the Edit Orders documentation again. It is strange though that I can only get the correct behaviour for the customer invoice by setting them differently.
Since there are two separate fields (one without tax and one with tax) in the invoice rows, they should each contain the appropriate correct information.
I presumed the behaviour is well-defined (according to the meaning of the field names which are very clear) when prices are displayed without tax (in both storefront and admin), but it turns out that is not the case. Maybe I incorrectly installed the Edit Orders files. It is not clear to me what the behaviour should be if prices are displayed (in store) with tax--it could be that the field is back-calculated for informational purposes, or else becomes irrelevant.