I've never had blistering in vinyl once the printer cleared the first few inches of the media, but even then it was heat setting related. There are more then just settings for dying and curing temps so something else might be off in your RIP.
We just upgraded to Flexi 12 and our L25500 started blistering in the first six inches in one particular spot and then it would clear up after the initial heat up cycle was finished. Something in the new installation of Flexi "broke" a setting that I had adjusted in the previous version.
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