Hello Alwina,
I am facing the same issue, my server name is EUSAPADHR01_HRP_30 it is properly displayed in table SAPWLSERV and SM51.
All my servers are newly installed NW 7.4 EHP7..
In table SAPWLSERV contents are as follows.
NAME INSTNO HOST LASTDAY INSTSHORT HOSTSHORT
EUSAPADHR01_HRP_30 30 EUSAPADHR01 03.04.2015 EUSAPA#1 EUSAPA~1
whereas in ST02 only if I click on the server name I am getting the history data, also it shows as - history data for server eusapadh_HRP_30 (its been truncated to eight characters)
I have checked in osmon table too there server name is populated as EUSAPA~1, not sure what the issue is.
Please help, also let me know if I need to delete the entry from table SAPWLSERV and execute the report RSSTAT98 to recreate the entries again will it solve my case.