I have number of items with keys defined as "tst[deviceN,parameterK]".
They can be updated using zabbix_sender if defined as type "Zabbix trapper".

Due to large number of devices that vary on different machines it is perfectly useful to define keys using macros as
{$DEV_01}=deviceN
tst[{$DEV_01},parameterK]
which work well for type "Zabbix agent" (configured with UserParameter).

However keys with MACROs defined as type "Zabbix trapper" are impossible to update using zabbix_sender.

There is no useful error logged: with "-vv" zabbix_sender basically just reporting "Processed 0 Failed N...",
neither there is a meaningful explanation of failure in server log (DebugLevel=4).

This appears to be a server-side error where MACRO is not expanded/substituted during communication with sender.