“Can gastric bypass surgery cause any health issues?”

Yes of course, there are many potential issues that can arise. Your surgeon should have discussed these I would think.
Here is a short list of potential issues:
post-operative complications/leaks, marginal ulcers, heartburn, nutrient deficiencies, iron deficiency, rebound weight gain in the long run.

Yes, gut motility issues and micronutrient issues, possible internal hernia with bowel obstruction.