Yes. Unfortunately I think there is no simple solution. And here I have to apologize. I don’t know what was I remembering but this computer is not able to boot other OS from the same disk. Probably when I used it time ago I had Linux on a second drive. As you have seen, the UEFI implementation is quite buggy. The only solution that came to my mind it’s to put the Manjaro’s EFI partition in a USB.
Yes, I noticed that I able boot Manjaro by using USB Manjaro installer. They said partition flag boot & esp problem but I install so many Linux none of them was able to boot. That how I know it was not flag boot & esp problem.
OK thanks anyway 
hi, I have an acer aspire laptop, and everytime I install linux using gpt/uefi filesystem I have to enable secure boot option in bios settings, then select a trusted boot drive from my installed system and that would lunch the os. but I didn’t used a dual boot system ever.
Hi, necrobumping a post from last summer won’t make forumers to go read and answer here.
Better create your own topic and explain there your issues.