A Reform source told BBC Scotland Bland’s departure came amid claims she was “difficult to work with”.
She had allegedly been called to a meeting last week to discuss high staff turnover within her parliamentary office, but Bland denied her resignation came as a consequence of that.
In a statement, Bland said her “principles and priorities remain unchanged” and that she believed she could best pursue her goals of “holding the Scottish government to account” as an independent MSP.
Under Holyrood’s rules, any list MSP who resigns their seat is replaced by their party’s next candidate at the last election.
As Bland is remaining as the Scottish Parliament’s sole independent, Reform now have 16 MSPs, one behind Labour’s 17.
That means they will not receive joint billing as the main opposition during first minister’s questions.
Offord described Reform’s slip into third place as “irritating” but said it would not “derail” their objectives.
He said: “We want people who are talented and bright and Amanda is talented and bright, but we also want people who are prepared to work as a team.
“One of the great things we’re doing at Reform is building a team.”
Reform UK leader Nigel Farage was asked about Bland’s departure following an event in Plymouth.
He said he “did not know the reasons” behind her decision, but that “parties losing people was always regrettable”.
Asked if Bland should stand down as an MSP, he said: “I don’t know the circumstances yet, but probably, yes.”
