When all of the required materials for a synchro summon of Ancient Sacred Wyvern are on the field, the game prints two script error messages. Wyvern cannot be summoned with those materials, even though other Synchro monsters like Ancient Fairy Dragon can be. It does not matter if the extra monster zone is not used, or if there are linked zones open. Confirmed to not work in Lan and YGOPRO servers, both EU and NA.

I have checked with two different tuners to see if anything changes. It did not. Because Wyvern specifically requires a LIGHT tuner, I tested Beelzeus of the Diabolic Dragons with a DARK tuner as well, but he worked without any problems.

The script error says
[Script Error]: expansions/live2017links/script/proc_synchro.lua:350 attempt to compare number with function
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Michael Lawrence Dee
Currently the anime repo contain all the obsolete scripts, wherein it contains an old script of Ancient Sacred Wyvern. As explained in the Card Scripts subforum, for Custom Card makers, bugs will happen to Synchros. This is the current case for Ancient Sacred Wyvern,

I'm waiting for the 2 fixes to get merged, a minimal fix to Synchros in the TCG/OCG repo and the important cleanup of the anime repo. Once they are merged, this will be fixed.
Now this is how I play: