AEL Developments Ltd - which trades as Easy Living - has proposed building 86 homes on the western edge of the coastal town to the west of Randolph Street, in a site it is calling "Castlegait".
Fife councillors wanted to see proof that a masterplan for the area, which the new application depends on, was signed off 20 years ago - only to be told by officers they couldn't find it.
The uncertainty surrounding the East Wemyss development centres concerns whether Fife Council is owed "developer contributions" as part of that masterplan.
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Most major housing applications in Scotland include some form of developer contribution to help the local authority to prepare for an increase in demand on local services. Contributions generally include financial payments towards education and GP provision, play parks and a number of affordable homes, the latter either built in full or paid for in part.
Council planners say no contributions are required because they were not part of the agreement signed off in 2002 - but elected members want to see proof that the masterplan was actually approved.
Councillor John Beare (SNP, Glenrothes North Leslie and Markinch) said that he could not approve the plans in good conscience without seeing concrete proof of the deal - adding that this did not mean he did not "trust" planners who recommended the plans for approval.
"My concern is that the masterplan is available but there is no record of it being approved or of any approval at committee," he said.
"I'm really at a loss how you can absolutely ascertain there are no developer contributions.
"I appreciate that officers have addressed it, but I would like reassurance that no contributions are required."
While just four formal objections have been raised about the plans, there are concerns over whether a village of around 2,000 people can support another 86 homes and hundreds of extra residents.
NHS Fife has expressed doubts that its existing GP surgery can cope with the demand of 86 additional homes, while East Wemyss & McDuff Community Council has raised queries over whether the primary school can do the same.
Cllr David Alexander (SNP, Leven Kennoway and Largo) is among those hoping for playground provision to be considered should it be found that Fife Council is owed extra money after all.
Easy Living has not included any children's play areas among its 86 bungalows, terraces and detatched homes, and the nearest playpark to the proposed site is on the other side of the A955 to the north - a main road with a 40mph speed limit.
"There should be some play provision here," Cllr Alexander said.
"There's 86 houses - there should be play provision."
The council's case officer Katherine Pollock defended the approach taken - and suggested a condition requiring a new pedestrian crossing across the A955 so children could cross safely.
However, Cllr Beare successfully moved postponing a decision on the plans backed by Cllr Derek Noble (Lab, Glenrothes Central and Thornton).
The application will likely be reconsidered at the next committee on June 9.