Custom user fields not saving after Joomla 3 to Joomla 5 migration

-- HikaShop version -- : 6.5.2
-- Joomla version -- : 5.3.4
-- PHP version -- : 8.3.33

We have recently migrated a website from Joomla 3 to Joomla 5 and upgraded HikaShop Business to version 6.5.2.

When editing a customer through the HikaShop administrator area, values entered into the following custom user fields are not being saved:

Field ID 29: e_CopyMinderKey
Field ID 37: e_Product
Field ID 41: e_MSValid

The customer record appears to save successfully and no error is displayed. However, the values disappear when the page reloads and remain NULL in the database.

We have checked the field definitions in #__hikashop_field. All three fields:

* Use field_table = user
* Are published
* Have backend editing enabled
* Are not read-only

The physical columns also exist in #__hikashop_user:

e_CopyMinderKey — text, NULL allowed
e_Product — text, NULL allowed
e_MSValid — text, NULL allowed

The field names and physical database column names match exactly, including their case.

We tested this against HikaShop user ID 1209 / Joomla user ID 10333.

Before saving:

e_CopyMinderKey = NULL
e_Product = NULL
e_MSValid = NULL

We then entered values into all three fields through the HikaShop customer edit screen and saved the record. A direct database query afterwards showed that all three values were still NULL.

The relevant query was:

SELECT
user_id,
user_cms_id,
user_email,
e_CopyMinderKey,
e_Product,
e_MSValid
FROM #__hikashop_user
WHERE user_id = 1209;

There are no related PHP, HikaShop or database errors in Joomla’s everything.php log. The save completes and redirects/reloads normally.

The database columns currently use utf8mb3_general_ci, although the values we tested were ordinary text and dropdown/radio selections.

The field configurations are:

Field 29:

* Table: user
* Name key: e_CopyMinderKey
* Type: text
* Published: Yes
* Backend: Yes
* Read-only: No

Field 37:

* Table: user
* Name key: e_Product
* Type: singledropdown
* Published: Yes
* Backend: Yes
* Read-only: No

Field 41:

* Table: user
* Name key: e_MSValid
* Type: radio
* Published: Yes
* Backend: Yes
* Read-only: No

Could you please advise:

1. Is there a known issue in HikaShop 6.5.2 affecting custom user fields after migrating from Joomla 3 to Joomla 5?
2. Are mixed-case legacy column names such as e_CopyMinderKey still supported?
3. Is there a database migration or field resave process that needs to be run?
4. Is there a particular request handler or HikaShop file we should inspect to see why these fields are being excluded from the update?
5. Could an administrator view override created under the old HikaShop/Joomla installation cause the fields to display but not be submitted or processed?

Thanks