Yesterday’s fixture at Warrington Wolves was called off on Saturday after FC reported a number of positive Covid tests.
The Multiple Cases Group advised a five-day shutdown from their last training session – Thursday – until another round of testing tomorrow.
Hull have played just 14 Super League fixtures this term – only Hull KR (13) have managed fewer while Wigan Warriors (18) have completed the most.
FC had won three on the bounce when defeating Huddersfield Giants on June 25 but then spent the next four weeks off: scheduled opponents Hull KR and Salford Red Devils both suffered outbreaks before positive cases at Hull also saw their match with Leigh Centurions called off.
Since then, they have lost against Huddersfield, Leeds Rhinos and St Helens before being forced into this latest shutdown.
Ellis said: “It is disappointing. The initial break really cost us and broke our momentum.
“Our performances hadn’t been perfect but we’d shown real grit and determination to get results.
“In previous years people had said we’d throw the towel in at times but they weren’t words being used about us earlier in this season. They still aren’t. But we’d had a couple of losses and there was a real desire to bounce back on Sunday.
“There’s just been more disruption again, though, and it is disappointing for everyone at the club. We’re just not getting any rhythm or any opportunities to find some form and it’s really hindering us.”
Hull hope to be able to visit Catalans Dragons on Friday and Ellis insisted: “Going to Perpignan, taking on top of the table Catalans away, gives us the chance to flip the whole thing right back in our favour and get that confidence and belief back going into the back end of the year.”