Checkout: brutto amount equals netto amount (tax not added) — cart module calculates correctly, checkout page does not

[OlafR]

Environment:

Phoca Cart 6.1.5
Joomla 6.1.2
PHP 8.5.9

Tax settings (all confirmed via Options screenshots):

Tax Calculation: Tax Inclusive Price (Brutto)
Tax Calculation (Sales): Tax Inclusive Amount (Brutto)
Tax Calculation (Sales) - Change Subtotal: No
Tax Recapitulation: Change total amount and rounding in calculation

Issue:
On the checkout page (#ph-pc-checkout-box), the .ph-checkout-cart-brutto field shows the same value as .ph-checkout-cart-netto, instead of netto + tax.

Example from a real order:

.ph-checkout-cart-netto: € 28,57
.ph-checkout-cart-tax: € 5,43
.ph-checkout-cart-brutto: € 28,57 (expected: € 34,00)

The order total at the bottom of the checkout page is calculated correctly (subtotal € 89,91 + tax € 17,09 = € 107,00, matching the original brutto product prices).

Important clue: the mini-cart module (mod_phocacart_cart, the dropdown cart in the header) calculates and displays the brutto amount correctly for the same cart contents. Only the checkout page view shows the incorrect brutto = netto value per line item. This suggests the two views may use different calculation logic for the per-line brutto amount.

Tested with a completely fresh session/browser (Brave, no cache) to rule out caching — issue persists.