Without accurate test results, it is impossible to diagnose or make proper recommendations. At best, all anyone can do is guess.
Each ppm of iron is equivalent to 4 grains of hardness whereas each ppm of manganese is equivalent to 2 grains. If the softener is exposed to either, then the 'H' setting would need to be set to a higher number than just the actual hardness amount. Some of the programming suggestions Reach4 provided are a guess as he suggested changing the hardness setting to 12 which compensates for 1ppm of iron in addition to your 8 grains of actual hardness. Your iron could be lower or it could be much higher.
A 0.25 BLFC X 27 minute BF = 6.75 gallons entering the brine tank. As each gallon will dissolve 3 lbs of salt, your current salt setting is then 20.25 lbs. Only 12 lbs of salt should normally be required to restore 35,000 grains capacity which is your current 'C' setting.
While a softener can be utilized to remove moderate amounts of iron, without regular ongoing maintenance, iron will eventually foul softening resin and impair its ability to function. Although you correctly performed an extra regeneration cycle, IF your resin is fouled, the extra cycle may have done little to remove the iron deposits, particiularly if your water pH is above 7.0.
Resin cleaners contain acid to assist the salt brine to clean away iron deposits. You mention ResCare and a feeder but the small quantity added with a feeder is more appropriate as a preventative maintenance technique as opposed to a corrective treatment for an existing condition.
For an acute iron problem, add the entire 1 gal ResCare bottle to a 3 - 5 gal plastic bucket, fill the remaining bucket with warm water, disconnect the brine line at the brine tank, place the line into the bucket, advance the controller to BD to draw the entire bucket of cleaning solution into the resin tank. To extend contact time, once the bucket is empty, shut off the incoming water feed and electrical power to the softener. After 10-15 minutes, restore power and water flow to permit the cleaner to be rinsed away during the remaining BD cycle. Remember to reconnect the brine line. Once the BD cycle has completed, advance the controller to initiate a complete manual regeneration cycle to help ensure the softening capacity is restored. Before initiating the regeneration cycle, reset the programming as Reach4 had suggested.
Edit to add: As some have now experienced Tannin issues that initally presented as being an iron issue, is there any musty or odd odor or initial off color to the water?