This is a known issue with some very rare server setups (in fact, I have dealt many times with the same issue in JoomlaPack and Akeeba Backup over the last 4 years). It has to do with the action URL parameter in the form. Fixing this problem for server setups like yours will cause the same problem for 99% of users, so it won't happen. Unfortunately, you'll have to bear with this behavior as long as you're hosted on that particular host :(
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
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