I have searched about this bug and i found it similar to this https://bugs.mojang.com/browse/MCPE-13983

It's almost the same bug except this only happens in Realms. It happens occasionally but since I have a redstone contraption that uses a lot of 4-tick repeaters (ex: LED glowstone lamp lights), it's a pretty bad bug. It does fix it self sometimes but then a few minutes later, the redstone repeaters work like 1-tick repeaters again. Note that this is on Realms and not on normal worlds. There is a way that I fix it (I just go ahead and destroy and replace the repeaters and set them to 4 ticks) but if I have to do that for every other moment, I'd rather not play. I hope this gets fixed