Currently, locks are working for cursors only. I mean, if you try to update/delete record using another cursor you will get an error since the record is locking by first one. UPDATE/DELETE sql statements ignore locks for now because we are going to implement "versioning" transactions (without any locks).
But, anyway, report it to the Mantis please.

Tested with local and remote db, within my application and ValentinaStudio, valentina 5.8.5 on Mac OS X
In ValentinaStudio,
1) make a SQL select command with RW lock, ServerSide
(SELECT myField1 FROM myDatabase WHERE RecID = 1)
2) open a new SQL tab and make a SQL update command on this locked record
(UPDATE myDatabase SET myField1 = 'SomeOtherValue' WHERE RecId = 1)
The update is done while the record is locked, without any error.

Are you sure that record is RW locked? Could you send me some example or at least select and update queries?
Is it local or remote db?