This was another test-the-water one-shot, published by MARVEL UK in late 1980.
It must have been deemed a sufficient success (possibly thanks to the amazing cover art) to return the next year as (the inappropriately named) BLOCKBUSTER resurfaced as a monthly with Omega, The Inhumans and Iron Fist. With a line-up like that, it's no wonder it didn't last the year.
Thor didn't reprise his slot for the ongoing series, presumably because he was already booked into VALOUR… followed by MARVEL ACTION and, before the end of the year, CAPTAIN AMERICA. He finally graduated to his own solo weekly, the first to appear with colour interiors, in 1983.