Hello,
This was also an issue in Football Manager 2022.
Step 1. Staff Responsibilities -> Transfer and Contract Responsibilities -> Offer to Clubs - Outgoing Development Loans, Senior, U21 & U18 Squad set to;
"Playing Wage Percentage" 100% "Unused Wage Percentage" 100%
Step 2. In "Squad" view, select multiple players in U21, right click, Transfer -> Offer to Clubs -> For Loan
Step 3. Offers come in all at, "Playing Wage Percentage" 0% "Unused Wage Percentage" 0%
Step 4. If I offer all players out individually, offers for "Playing Wage Percentage" 70% - 100% "Unused Wage Percentage" 70% - 100% come in.
As mentioned in Step 4, if I offer individually, they do receive clubs willing to pay the percentages, so it is not that they are not desirable, but the initial mass offer is set to 0% and not following settings in responsibilities.
Hope this helps.