The Financial Conduct Authority (FCA) is to work with trade associations and asset managers to solve the potentially harmful impacts on consumers of the Packaged Retail Investment and Insurance Products (Priips) rules.
In its business plan, published yesterday (April 17), the regulator stated it would continue to work with firms to address the issues they are facing.
The FCA had already published a series of papers on the issue, which centres on the future performance projections that must be included in the key investor documents produced by fund firms.
These projections must be calculated based on the performance of a fund over the previous five years but because markets have enjoyed a period of consistent rises over the past decade, the projections of the future may be unrealistic.
The FCA stated: "The Priips regulation introduced a requirement for firms to produce, publish and provide investors with a standardised key information document for Priips.
"This was to help investors make better and fully informed decisions by being able to compare key features, risks and rewards.
"Firms have raised concerns about this requirement.
"In response, in July 2018 we published a call for input to gather information on any unintended harms, and subsequently our feedback statement in February 2019.
"We will continue to work with firms and trade associations on what we can do to resolve the issues identified."
Simon Fraser, chairman of the F&C Investment Trust, said the rules could lead to a "potential miss-selling scandal".
He added: "Throughout my career I have been told that I cannot say past performance is a guide to future return, but apparently now I have to."
The rules at present only apply to investment trusts, but were scheduled to be applied to unit trusts from 2019, until this was postponed until 2021.
FCA chief executive Andrew Bailey has previously said "action is coming" on the Priips rules.
The rules also include a requirement for firms to include a measure of the riskiness of an investment.
Ian Sayers, chief executive of the AIC, the trade body for investment trusts, said there is a danger this risk weighting makes VCTs seem less risky than they are, and could "mislead" investors.