Download / Upload on Customize form problem

I have an ERPnext v9 OVA since Sep 2017, switched it to production, applied several customizations (new fields and print formats only), added data, updated to v10, keep updating it once per week. So far so good.

Last week I successfully installed ERPnext latest v10 on a fresh Debian9 VPS as production. Both the OVA and the VPS are on the same ERPnext & frappe version (v10.0.22 & v10.0.23 respectively).

OVA is the source
VPS is the target

I downloaded the Customer “Customize form” CSV file from my OVA which contains 49 rows. The VPS showed 44 rows as default. I uploaded the CSV file to VPS, it answered “uploaded”, “updated”, I hard-refreshed the page just in case and… VPS: 44 rows. So the customization upload did not apply on the VPS although the ERPnext replied everything was OK. Note that the VPS’s Setup > Error log shows nothing at all.

A few months ago, the Customize form > Upload functionality had problems that were promptly fixed. I can only guess that some update broke the functionality again.

Can this problem be fixed?