Spring Boot, Thymeleaf, Error during execution of processor - spring-boot

Question

I have this thymeleaf template and I cannot find a way to make it work. The thymeleaf template is coded to do a post form like this:
<form class="mx-auto" method="post" th:object="${provideForm}">
<div class="mb-3">
<label class="form-label">Paciente</label>
<select class="form-select" th:field="*{pet}" >
<option selected>Seleccione su Mascota</option>
<option th:each="i : ${p}" th:value="${i.index}" th:utext="${i}"></option>
</select>
</div>
<div class="mb-3">
<label class="form-label">Servicio</label>
<select class="form-select" aria-label="Default select example" th:field="*{service}" >
<option selected>Seleccione el Servicio</option>
<option th:each="i : ${s}" th:value="${i.index}" th:utext="${i}"></option>
</select>
</div>
<div class="mb-3">
<label class="form-label">Lugar</label>
<select class="form-select" aria-label="Default select example" th:field="*{veterinary}">
<option selected>Seleccione la Veterinaria</option>
<option th:each="i : ${v}" th:value="${i.index}" th:utext="${i}"></option>
</select>
</div>
<div class="mb-3">
<label class="form-label">Fecha</label>
<input type="date" class="form-control" id="exampleInputEmail1" aria-describedby="emailHelp" th:field="*{date}">
</div>
<div class="mb-3">
<label class="form-label">Hora</label>
<select class="form-select" th:field="*{time}">
<option th:each="i : ${#numbers.sequence(0,6)}" th:value="${i}" th:text="'1' + ${i} + ':00:00'"></option>
</select>
</div>
<button type="submit" class="btn btn-primary">Agregar</button>
<button type="button" class="btn btn-outline-danger">Cancelar</button>
</form>
The spring boot is trying to pass the arrays like this:
#GetMapping(value="/appointmentsView")
public ModelAndView appointmentsView(){
if(!Objects.nonNull(authUser)){
return login();
}
updateInfo();
ModelAndView mv = new ModelAndView("appoitnmentsView");
List<String> displayPets = new ArrayList<String>();
for(Pet p : pets){
displayPets.add(p.getName());
}
mv.addObject("p", displayPets);
List<String> displayServices = new ArrayList<String>();
for(Services s : services){
displayServices.add(s.getService_name());
}
mv.addObject("s", displayServices);
List<String> displayVeterinaries = new ArrayList<String>();
for(Veterinary v : veterinaries){
displayVeterinaries.add(v.getVeterinary_name());
}
mv.addObject("v", displayVeterinaries);
return mv;
}
I am always getting a 500 error code:
org.thymeleaf.exceptions.TemplateProcessingException: Error during execution of processor 'org.thymeleaf.spring5.processor.SpringSelectFieldTagProcessor' (template: "appointmentsView" - line 38, col 47)
at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:117) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
at org.thymeleaf.processor.element.AbstractElementTagProcessor.process(AbstractElementTagProcessor.java:95) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
The only way I could fix this problem is by moving the th:field that are on the select tags to the option tags. However, by doing that it always return null on the th:field