i doubt its a bug, it seems to be lag
have the very same problem here every day after noon.
its not at my end, but you can be sure its not at the end of the site either.
the problem is either at your end or if you are fine with your connection on the way in between with one of the servers you run through till reaching d2jsp.
some of them seem to cause problems at certain times or so. im not an expert on this unfortunately, but its not in our hand to influence this i fear.
try different times of the day and adjust your way playing to it. e.g. i can glyph without problems in the mornings.
therefore i collect glyphables or do other stuff after noon and glyph it the other day in the morning when lag is gone for me.